Professional quality free fonts*
Ralph is behind the excellent Inconsolata font which is great for printing code or if you like large programming fonts. He also has a number of classical typefaces including the great ATF Century Catalogue, Museum Caps, LeBe, ATF Bodoni and ATF Franklin Gothic.
Microsoft OpenType Font Pack
A bunch of licenced fonts available from Ascender Corporation including the stylish Kooteny and sharp Miramonte.
Jos has produced a number of beautiful typefaces free to download. I particularly like the subtle quirks of Delicious and the flowing curves of Fertigo (sample shown_ but also check out some of the others available too.
These fonts were previously commercial and designed for the Greek alphabet and the four fonts available – Canonica, Cosmetica, Modata, Moderna – look great in the Latin alphabet too.
A number of experimental fonts for download but not redistribution including the rather delicious Engel Light ltd.
These people produce a number of great free fonts including the elegant COM4t Fine Regular and Quilline Script Thin.
If you love typography then check out the ILoveTypography blog for news on great typefaces and tips on designing your own font.
* some restrictions apply to usage on some of the fonts, check the licences for details.