GroupMe allows you to create a group, add people to that group and get a free number for that specific group of people.
You can now text a message to that group number and everyone in that group will get your message. Or you can call that group number to do conference calls.
Create a group for family, friends, groupies, bookies or whatever.
Note: For Android version 2.1 +
Download GroupMe for free from the Android Market.