Apple Discussions
Easy to navigate, convenient searching, and handy bookmarking all make this site stand head and shoulders above the rest. What does Microsoft do? Shove you into Usenet. While that may make sense for the Net-savvy developers, my mom sure wouldn't do well there.

Adobe User to User Forums
Classy design and powerful tools separate Adobe from the rest. They also go a long way toward fostering community in the forums, adding Featured Hosts and the Guest Spot Forum where visitors can "talk with special movers and shakers in our community."

AVS TiVo Forum
The passion the users show for their beloved TiVos on this site more than makes up for the cheesy icons and spotty toolset. This is the central hub for all things TiVo.