Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I'm a BIG fan of BusySync (www.busymac.com). I use it to sync my iCal to Google to my co-worker's gCal to his iCal - and back. Within 5 min of adding something to my iCal - it is on his iCal.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.