This is pretty useful, I am working on another site but it won’t be much of a social site, but I am definitely using quite a few of the plugins in this list. (instead of acts_as_taggable_on_steroids we’re trying to use acts_as_taggable_on). I also think cache_fu will be a must-have if you ever think the site is gonna have real traffic.

Building a Social Network Site in Rails | Jim Neath