Sources of various more or less free fonts

Notice that “free” is to be taken with considerable amounts of salt — the fonts can all be downloaded without breaking any laws (I hope!) but be sure to check the details for each font before using or redistributing it!

GhostScript
Clones (from URW) of all the standard PostScript fonts, including old standards like Times, Palatino and Helvetica.
GhostPCL
Large overlap with the Ghostscript fonts, but some new ones too, such as Garamond no. 8 and URW Classico, an Optima lookalike.
Bitstream Vera
A set of a serif, a sans-serif and a typewriter font, all very nicely hinted for on-screen usage.
Microsoft
The Microsoft Core Fonts, including the ubiquitous Verdana, Georgia and friends.
TrueTeX
Truetype versions of the Computer Modern (“the TeX font”) family in Windows 1252 coding. Also the Belleek font, designed to work as a drop-in replacement for the Mathtime fonts in TeX.
Microsoft Reader
The Microsoft ebook reader comes with Truetype versions of Frutiger and Berling.
Sun JRE
Sun's Java Runtime Environment has Truetype versions of the Lucida family from Bigelow & Holmes.
Gentium
A serif font with roman and italic versions in TrueType format. Contains a reasonably large Unicode subset.
Baramond
Another Garamond clone.
FPL
A Palatino clone, supposed to have smallcaps and oldstyle numbers.