http://www.alvit.de/blog/article/20-best-license-free-official-fonts

(Be careful of using the 'F' word here.. Some don't like it :/)

Lido

more to browse through

Friedman's site is a nice list, but note that not all of the ones listed there are actually free for commercial use. So be sure to read the fine print.

Bitstream vera is one of my favorites, though it only comes in standard and bold:

http://www.bitstream.com/font_rendering/products/dev_fonts/vera.html

Personally, I think it works better as a display face than text face.

Quality + free is very hard to find in a serif face. (There are however plenty of free, interesting one-off display faces). Georgia works great on screen, not so well in print, (but it was good enough for the Kerry campaign). Gentium is an interesting one, but I've never used it.

What I meant is... you can more easily get away with a low-quality sans, if low quality is the look you're aiming for. But with serif faces, that approach rarely works.

[ post deleted, link working now ]

Friedrich Althausen's Vollkorn-Brotschrift is great. It is published with a creative commons Licence.