There's a nice collection of links to Open Courseware here. I might as well also here mention Gigapedia. It's an incredible linkfarm to high quality PDFs of mostly copyrighted material, including a HUMONGOUS number of philosophy books. (Who scans these?) You can login anonymously using BugMeNot, if you prefer that to registering. (Logging in is required in order to search the site.) And remember, it's not illegal - surely! - to download a copy of a book you already own! Of course, I can't be blamed if you succumb to temptation, but honestly, the free dissemination of information not everyone can afford access to isn't that bad, it? And let's be serious. What professor of philosophy would object to you downloading their book? The objection couldn't possibly be on the basis of the royalties they would otherwise receive.