TextPayMe - The Next PayPal
TextPayMe is a new service that I just learned about from Scott Hanselman. Basically, it lets you send money to anybody via your cell phone. You just send a text message to the number of the person you want to pay. You will get back a confirmation phone call during which you enter your PIN to verify that you really wanted to send the money. This is very secure, because only you should have your phone, and only you know your PIN (if someone else "borrows" your phone).
What's more, if you sign up during the beta, you are guaranteed not to have any transaction fees ever (that would have been nice to have for PayPal), you get $5 in your account to play with, and you have a chance to win an XBox 360. It takes about 3 minutes to sign up -- just click the link above to try it out.