Buxfer -- Very clean app that tracks transaction among a group of friends who share expenses, such as roommates and college students.
Geni -- My exact idea in 2005 executed (and valuation at $100M already as of Q2 2007; only started in Q3 2006). Terrific Flash app that lets you create new nodes in the tree, then when the family member signs up they can take over their own profiles
Ning -- "Create your own social network" is the tagline. But does not appear to be any more special than a MySpace group?
Tubes -- Peer-to-peer file sharing and auto sync
Genesis Exchange - Online marketplace for Angel investors
Stockpickr
Team Snap
Talent Spring -- Resume ordering by crowd votes
- Protrayl
- Ficlets
- Farfarazzi
Etsy - Marketplace for handmade items
Foresight Exchange
Trax In Space - Ratings and Reviews network for musicians and fans
% Completion -- Great way to motivate users to complete actions that you want them to do, such as filling out their profile. Used on LinkedIn, Geni, etc.
"Take the Tour" -- We need this on Work.com and Business.com