Pictures:

• Flickr
• Deviantart
• Photobucket
• SmugMug

Social Networking:

• MySpace
• Twitter
• Facebook
• Technorati

Music:

• MySpace Music
• Last.fm
• Odeo

Stores:

• Amazon
• eBay

Reference:

• Wikipedia
• Answers
• IMDB
• Dictionary.com

Search Engines:

• Google
• Yahoo
• Live
• Ask
• Snap

Google's:

• Images
• Video
• News
• Blogs
• Maps
• Groups

Bookmarking:

• Del.icio.us
• Digg
• Reddit
• Furl
• Blinklist
• Simpy
• Clipmarks

News:

• Slashdot
• Newsvine
• NY Times
• CNN

Video:

• YouTube
• iFilm
• MetaCafe
• Daily Motion