I love movie trailers! In a lot of cases, a trailer can rule even when the movie sucks. There are a lot of cool trailer sites out there, and a lot of different formats and quality levels. Classic movie trailers are a little harder to find, while the newest trailers are everywhere. Plus, if a trailer was encoded long ago, it's lower quality, especially for quicktime files. When I'm looking for movie trailers, here are the best places I check first:
trailers.apple.com the best place to get high-quality quicktime copies of all the newest trailers! I check that site about once a week. Plus, if you have quicktime pro you can save them all!
videodetective.com has the most trailers I've seen online. Just about everything, with a few exceptions. Medium quality, but the selection's great! This is where most IMDB entries link to for trailers.
Movie-List Classics has the best quality trailers for a ton of all time classics! The rest of the site has new and old trailers, but some don't work. The classics section is a must see though, you'll watch all day!