Public Domain Torrents is a site that hosts torrent files for many feature films that are now in the public domain. They have a decent SF section with over 150 movies available. Of course, you don’t get Forbidden Planet, but you do get Teenagers From Outer Space (“The high court may very well sentence you to TORTURE!!!!”). In fact, I see several movies that have been featured on Myster Science Theater 3000. They PDA, iPod and PSP versions available, and some movies are even hosted on Google Video for those of you without bittorrent or one of the above listed playback devices.