The way I've found most of my music is that I went to the site of a group I liked and checked their links page. If I liked something they linked to, then I'd check that link page as well.
Also, if you're into electronica, you should look at some of the stuff on Nectarine.
The thing is that it's not necessarily a file that has the extension. A.pbproj like mentioned in one of the replies is actually a folder, but it's treated like a file because of its extension. Same with application bundles. Run file on one and it returns that it's a directory.
Any mp3 player that requires any kind of database or other data structure other than reading the card and the tags is over-engineered and is probably full of DRM junk.
Apple's been good about DRM. The only real protection on the iPod is that the software asks you if you want to wipe the music library after connecting it to a mac other than its home system. The database is more for fast booting, caching tags, and some data that doesn't belong in the id3 tag (like equalizer settings and song-specific volume adjustment). It's a practical solution.
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The way I've found most of my music is that I went to the site of a group I liked and checked their links page. If I liked something they linked to, then I'd check that link page as well.
Also, if you're into electronica, you should look at some of the stuff on Nectarine.
The thing is that it's not necessarily a file that has the extension. A .pbproj like mentioned in one of the replies is actually a folder, but it's treated like a file because of its extension. Same with application bundles. Run file on one and it returns that it's a directory.