Seeqpod is a music search engine that scours the web for mp3's hosted by various sites, embedded in articles, linked to in blogs, etc. It's at its at its core a vertical search engine for the web, purely focused on music. Built around the search engine, though, is a fully functioning media center - you can play the mp3's, make playlists, save files, and more. And if you follow the URL's, you can download the mp3's direct from the sources. In a few random search tests, I found all of the songs I was looking for - this one seems like a great resource for free music mp3 files on the web!