Drop.io has some interesting possibilities. You don't have to give them any information, just click to create a page (drop.io/whateveryouwanttonameit) and you have a place to drop files. You can share those files, but drop.io goes a bit beyond that.
There's a phone number for voice mail, an email account, a way to send and receive faxes, a conference call number, and an rss feed.
So now I can call, send a voicemail to myself, and it will show up in my feed reader. This is helpful when I am away from the computer and I think of that thing I need to do the next day.
Drop.io is designed as a collaborative workspace, so I'm sure those who run in groups will find it particularly helpful. I'm just trying it out right now, trying to figure out how I can use the service.