IMDb
The Internet Movie Database. Exhaustive data on movies and actors. Find almost anything with a search. Excellent linking to other pages & other sites.
TV.com
TV Guide. Find out which episodes of your favourite shows have been aired, and read reviews and synopses.
YouTube
This has become an amazing media resource, as people upload more content of their choice. If you can live with the low resolution pictures, you can find almost everything here: music videos, songs from concerts, clips from TV shows, etc. YouTube now has an option to view content in full-screen mode, which is great as long as the media themselves are high enough resolution.
The Pirate Bay
A great source of torrents, for getting music and videos (TV and Movies).
Torrent Downloads
A good source for some torrents.