This time its the Salvation Army (over in the US). They are offering people a chance to download a bell (you can get yours here).
A downloadable bell on a telephone might sound a bit obvious and not very exciting if you live in the UK, but anyone who has visited the USA at Christmas can't have failed to have seen (and heard) the hundreds of bill ringers who raise tons of money for the Salvation Army.
This App gives you the chance to go out and join them or do your own impromptu collection - without the need to hunt down a real life bell!
There's a video that shows how it works here (jump to 4 minutes 20 seconds as the rest is not relevant).
There is even a direct link on the App to give a donation to the Salvation Army.
And if you haven't had the chance to see a bell ringer in action, this video has a very nice clip of one being given a helping hand by a few flash-mobbing professionals.