This is free-as-in-beer for the most part but the article seems to be good at mentioning the license (i.e. non-commercial, SIL license, etc.)
There’s also good programming (monospaced) fonts out there. I remember back before GNOME secured the release of Bitstream Vera that pretty much the only choice for programming fonts on X11 was “fixed” or Courier. Nowadays we have a slew of good fonts available. Quite a few are listed in this Hivelogic post, although about half are not freely available. I do agree with the choice of Inconsolata though. One other good monospaced font I would mention is Envy Code R (free to use but redistribution prohibited).
The only problem I’ve noticed so far is that the Aller font is rendered with spaces elided in some situations (notably JuK’s track announcement popup), which I can’t figure out.
Are there other good, free fonts out there that I’m missing?