The iPad and iPhone both offer Push notifications, but not every application or web service has been upgraded to use them. Boxcar acts as an intermediary, letting you know as soon as anything happens, whether it's on Twitter or RSS, Facebook, Foursquare, Reddit, Google Buzz or more. And it does it very well.

The real problem isn't with the Boxcar app itself, but with Apple's handling of Push notifications. They're incredibly disruptive, taking you away from whatever you were doing and completely taking over, to the point that getting more of them is likely to be the last thing you want.

It's one thing to take out your iPhone and see at a glance that you have a new message, but the same thing popping up in the middle of a movie or game is just annoying.

What makes it even more of a problem is that while Boxcar will alert you to updates from multiple services, its badge can only show you how many alerts you have waiting, not whether they're important. Both of these things render it less than useful, although it does an excellent job if you don't mind the downsides of Push notification.

It is, of course, only a stopgap measure, as more and more applications take the job over directly.

For the iPhone, Boxcar is still a handy tool. On the iPad, however, you're probably best off avoiding it. Whatever you do though, don't ask for Push notifications on something like #wikileaks, or just fighting your way to the screen that lets you turn it off will become a nightmarish odyssey in its own right.

The App Store is groaning under the weight of tip calculators, but they're of limited usefulness. Even beautifully finished apps like Tipulator just have you enter the total of a bill from a bar or restaurant, telling it how many people are in the group, then they add a tip and split it.

But what if you had soup and your friend plumped for a rib-eye steak? Or if three of you had a soft drink each, but a couple shared a bottle of wine? And what if Sandra has the correct money, but Peter only has a fifty pound note? And the tip? Shall I just leave a tenner? Bistromath solves all this.

It only takes a few taps to enter the cost of the meals everyone's having – if you want to take the time, you can tap through and pick from a handful of configurable options to keep track of whether you're entering a drink, a main, a side or whatever – and the real genius comes when you realise that you can define anything as being shared among more than one person.

A bowl of chips that three of you stole from? Easy. The cost is split three ways and apportioned to each of the three. You can type people's names in manually, or hook into your Contacts app to pull them in, which also shows people's photos if you've tied them into the address book database. Or you can add them in Bistromath.

Once you're done, and have decided on a tip percentage, Bistromath shows you how much each person owes. Better still, you can tell it how much each person has put in the pot, and it will calculate how much change they need. You can even email receipts to the folks who were at the meal.

It's a little US-centric at the moment, but it works fine in the UK. And as if that wasn't enough, up to four other people can collaborate on a bill wirelessly with no complicated setup.

Using Awards, you can track achievements for your children, staff and more.

You begin by adding people from your Contacts list (which is handy, since it means it’s easy to issue awards to the email addresses on these entries), then go on to award gold stars.

You can either add them manually or tap a task – ‘tidied room’ or ‘handed work in ahead of deadline’, for example.

You can create your own tasks and assign them a star value, then add them to that person’s history. Then you set appropriate rewards – ‘an hour of TV’ might be worth 5 stars – which you can issue and redeem via email as pretty graphical certificates.

Configuration can be a little tedious, however, and we’d like to see some tie-in with a web service so that the people you’re monitoring can see what rewards they’re eligible for.

Postman makes little virtual postcards on your iPhone, and lets you share them using Twitter, Facebook, Tumblr, email and more.

You can snap a shot with your iPhone's camera, load up a saved photo – or choose from a small catalogue of stock landmark shots – or even grab your current location on a map in Map, Satellite or Hybrid view, and then add some text.

Flip it over onto the back and you can write in a message; you can also disable the front or back. The UI is lovely, and there's a range of themes you can add. Changing the text size, style and colour is easy, but at the moment you can't resize images – coming soon, though.

It's easy to share your cards too, though there's currently no way directly to send via MMS; you have to save it as a photo, then MMS that instead.

In order to avoid walking into people and vehicles when emailing while walking, we have this little app, Email 'n Walk.

Fire it up and you're presented with a live video feed from the rear-mounted camera, with white text displayed over a translucent black background – and you can enter a subject line and the body; when you hit Send, it passes your text to the Mail application for addressing.

As far as it goes, it works, but the angle at which you naturally hold your iPhone when composing a message means you're unlikely to get decent warning for cliffs/lamp-posts/dog mess.

We were thrilled when the cuddly folk at The Iconfactory brought us Twitterific – the first proper iPhone Twitter client. But, recently, its simplicity in the face of burgeoning competition was beginning to hurt it. However, Twitterrific 2.0 has now arrived, and it has a radically beefed-up features list.

At first glance, it looks less 'rich' and more 'complicated'. We recommend watching the 'tweetorials', in fact. Indeed some of the really cool and really basic stuff – conversation threading and even just profile lookups – need to be configured through the settings.

The interface is lovely, though, and the Twitterrific model – your tweets, mentions, messages all in the same view, colour-coded – feels completely natural. If you wish, you can filter the list temporarily only to show favourites, mentions and more. And there's now finally the support for multiple accounts, trends and searches.

After initial confusion, we're converts. There's little it can't do, although reposting between accounts is tricky.

It has lots of little touches such as the ability to collapse the keyboard while composing a tweet to see the list, and even tap on hashtags and usernames to add them to your tweet. A complete joy to use.

At first glance Birdhouse might seem pointless. If you thought Twitter was vague, indulgent and pointless, look away now; Birdhouse is a notepad designed to let you draft multiple notes for Twitter and publish them when you choose.

Frankly, we think the idea has some merit; you may not always want to publish immediately, you may want to check some facts or even just some spellings, or you might just want to organise thoughts for multiple accounts. Besides, if you think it's pointless, don't buy it.

As it stands, it's a beautifully polished app that performs its stated function well. You can rate drafts and even unpublish notes that were added from Birdhouse.

The iPhone's multitouch system, GPS and 3G connectivity make it the perfect portable Twitter device, and there are several great programs that take advantage of it.

Twitterific is our favourite, purely for the clean interface and the excellent way that it distinguishes between different post types, but others include Tweetie (with an interface reminiscent of the standard iPhone SMS system) and the GPS-enabled Twinkle.

Twitterific doesn't offer the obvious 'killer' iPhone feature of showing you posts made near to your geographical location – something that can come in useful at events, if not necessarily while walking home – but it handles everything else with aplomb.

It's available in two forms, an ad-supported freebie version and the £6 Premium version.

The only real annoyance is that there's no way of telling it whether to start the scroller on the latest posts or snap back to where you left off – a real nuisance if you use it to catch up on posts every now and again rather than as your primary Twitter reader.

Both versions have their use, but be prepared to waste a lot of time scrolling to see what's new.

Twitter client Twitterific can be a little sluggish, it doesn't make as much use of the iPhone's location-awareness as Twinkle, and the free version features (acceptable and unobtrusive) ads, but it gets our vote because it's so very polished.

It looks beautiful, there's lots of attention to detail, and the inline help system is superb. We love the inline browser, so tapping on URLs doesn't bounce you out to Safari, and you can get info on your Twitter friends. There's no background notification obviously, but that'll be killer when it's rolled out. An ad-free version costs £5.99.

Facebook's iPhone-optimised website is one of the best around, so we had high hopes for the native application. It's certainly faster than the web app, and it feels slicker and more consistent with the iPhone's user interface.

While the very first release lacked a few features that many regarded as essential – no way to write on walls, or see users' photos, things the web app were perfectly capable of – the quickly-released 1.1 version of the app added in these and more. There's a dedicated photo capture button that can upload your photos directly to Facebook, too, and of course you can now upload photos that you've taken previously. Once the Push Notification Server is rolled out, this will get even better, especially with Facebook Chat.