Last week at a New Tech Meetup I got a preview of Radio Handi, a company that's rolling out some useful group communication services. The one I like the most is the free phone conference system that uses email for setup. You email a note to the people you want to have a phone conference with, and bcc "invite@radiohandi" as well. Shortly, the Radio Handi bot emails all the attendees with the dial-in bridge number.
Why it's great: There's no previous signup required, you don't have to set anything up on a Web site, and it's free. Well, sort of: the call to the conference bridge is in the 712 area code in the U.S., so toll charges may apply. There are also 30+ international numbers. The service is also available directly via a SIP-based VOIP network (but not Skype, unfortunately).
There are several free reservationless teleconference services, but Radio Handi is the only one that I know of that lets users bypass the Web signup if they want, and do everything on email.
Radio Handi will soon be adding other services, like a feature that can turn any phone conference into a live MP3 stream. That makes any cellphone essentially an Internet radio station, which is pretty cool. That should roll out this week. Also, the company is buying a big block of phone numbers, and may eventually give out temporary-use phone numbers for conferences, instead of a number and an access code. That will make conferences easier to dial in to.
The service also has text features. It lets users manage email and SMS discussion lists, and can turn SMS into a group chat (see also: 3jam).