If you're among the die-hard band of hold-outs that has yet to recognise the power of micro-blogging site Twitter, then a stunning demonstration of its power for good may change your mind.
Global non-profit group charity: water is currently using Twitter to lift awareness of its drive to bring clean water to the 1.1 billion people worldwide who currently don't have access to it.
Its next fundraiser, on 12 February, will involve participants in over 100 cities across the globe, all organised through Twitter.
The so-called Twestival 'Tweetup' – a meetup made on Twitter – was set up in just 24 hours – enough time to get people in 40 main cities involved.
Once the ball was set rolling through Twitter word-of-mouth, the rest soon followed, with the result that the February fund-raising event is already well known and has been blogged about from Sydney to Lima.
The minimal effort needed to follow plans made on Twitter is clearly a factor in boosting participant numbers, so there's no excuse for not checking out the city list on the Twestival website.