from Lifehacker by Adam Pash
Rely on AIM as your nerve center of workplace communication? You can forward instant messages to your cell phone whenever you're not signed on using the Mobile AIM Service. All it takes is an AIM username and password (that is, you don't have to use the AOL Instant Messenger program as your chat client; you just need an account). After you register, your AIM profile will change to "On JiveTalk" whenever you log out of AIM on your computer and all new IMs will be forwarded to your phone via SMS (that means you'd better have a good SMS plan if you expect to receive a lot of mobile IMs). To unregister your phone, just send a dummy SMS message to 265021. For more details, check out their IM Forwarding Users Guide (PDF alert).