Ah, convergence - that lovely marriage of previously separate things to create a magical third - think peaches and cream, Batman and Robin, Linux and the Eee PC.

When convergence works (step forward iPhone) it's wonderful, but some arranged marriages go very badly wrong - just look at the Amstrad Em@iler.

Welcome to the best / worst examples of both in Convergence Gadgets: The Weird And Wonderful:

HEAVEN: Apple iPhone

Easy one this. For years tech-makers trying to get all their know-how into a single device, and then Apple comes along and does it, causing a collective slap hand on forehead.

The iPhone enables you to make and take phone calls (duh!), serve the internet, play music, watch movies, play games, find your way around and check the weather without ever pausing for breath.

The real killer, of course, has been the Apple iPhone's multi-touch user interface. It's actually made all of the iPhone's nefarious functions properly useable - which is more than be said for most of the applications in some of its rivals.

Taser c2 with mph holsterHELL: Taser C2 with MPH holster

The road to convergence hell is littered with devices that share one common theme - the uncanny ability of tech makers to shoehorn MP3 playback into anything and everything no matter how bizarre. The Taser C2 with MPH holster has to be one of the oddest examples yet.

The Taser C2 is, of course, a non-lethal weapon that can stun anyone who comes close with a jolt of electricity that's enough to incapacitate them while you make a getaway. 

Tasers are so 'good', several UK police services (not forces, remember) already use the professional versions to take out hoodies and the odd diabetic, but it's the consumer version we're looking at here.

The Taser C2 is aimed at ladies with a taste for pink, leopardskin and other natty patterns and is offered with a optional MPH holster accessory that can be used to store up to 1GB of MP3 music - so you can bop while you stop the baddies.

Already dubbed the iTaser by bloggers, the Taser C2 sadly isn't available to own in the UK. You can buy one Stateside for around $80 (£40)

HEAVEN: Sony PlayStation 3Sony playstation 3

If anything qualifies as a home entertainment hub for the 21st Century, then the Sony PlayStation 3 is probably it.

By design the PlayStation 3 is a cutting edge games console, high definition Blu-ray and DVD movie player, audio CD player and a Wi-Fi-enabled internet appliance. Plus you can also use its 40GB hard disk drive to store music, photos and video too.

Compare the PS3 to its rivals in convergence terms and not even the Xbox 360 comes close - largely because the HD DVD drive was only ever included an optional accessory, and now HD DVD is defunct.

Sony's also managed to wrap up all this technology in a pleasingly usable interface and a glossy, understated case design that hints at the power within. We love it.

Amstrad em@ilerHELL: Amstrad Em@iler

Now (in)famous for being Britain's most famous entrepreneur, Sir Alan Sugar has also proved to be a woeful judge when it comes to good tech.

Not content with saying that the iPod would be a flop, he also monumentally misjudged the public's appetite for the Em@iler - an internet-connected home that enabled the PC phobic to send and receive emails.

The concept seemed noble enough, but the execution was horrible. For the original Em@iler (even the name makes you shudder) was a Frankenstein product.

It married a cheap-looking home phone with a wired pull-out QWERTY keyboard and a laughably bad monochrome LCD display. Its successors weren't much better. Why?