Your help is required Directory

I'm trying to create a list of the current most effective/user-driven in the social networking/software space:

del.icio.us - social bookmarking site
Frappr -
Friendster - dating site
Flickr -photo posting/sharing site
Stumbleupon - web site ranking
MySpace - friend networking
LinkedIn - business networking

Meetro - radius and proximity based networking
Artboom artist networking
Ryze -business networking
Passado - friend networking (Europe based)
Open BC - businesses networking
Tribe.Net -friend networking
Xanga - friend networking
Facebook - friend networking through schools
Ecademy - business networking
Orkut – friend networking (currently mostly Brazilian users)