I just spent a while adding events in iCal, and I thought of a cool feature.
Integration where Adium would look at your iCal events and automatically update your away status message. That way your buddies can see if you are in class, studying, at work, on lunch break, in a meeting, doing a presentation, whatever.
There is integration with other Apple apps in Adium (Address Book, iTunes now playing, inserting Safari links) so maybe iCal support can come in the future? I know Growl can (or at least it could) display iCal events so I'm sure it's possible.
iCal integration idea
Didn't search the xtra's site, huh? Granted, it's not perfect, but..
http://adiumxtras.com/index.php?a=xtras&xtra_id=1403
http://adiumxtras.com/index.php?a=xtras&xtra_id=1403