TerraIM is an instant messaging client that connects to the AOL Instant Messenger network. Thus, one can use TerraIM with an existing AIM, ICQ, or AOL screen name. Just log in using your AIM screen name or ICQ number with TerraIM, and your regular buddy list will show up.
TerraIM has several useful features:
Thanks to DoorManBot, you can send messages to people who are offline. The messages are delivered once the person signs on, even if you have signed off by then.
TerraIM easily fits on a floppy, and requires no install. It is perfect for environments where AIM cannot be installed, such as school networks.
set an alias for a buddy and that alias is displayed everywhere instead of the person's screen name.
login directly to invisible mode, so no one suspects that you are online
TerraIM implements real time logging. All instant messages can be recorded to files.
leave TerraIM running at home and remotely check messages, change the away message, and download files.
you have the option of having all your instant messages with one window, with tabs to switch between them.
TerraIM is fully skinnable. Though currently there are only few skins available, more are being developed.