mimetex, licensed under the gpl, lets you easily embed LaTeX math in your html pages. It parses a LaTeX math expression and immediately emits the corresponding GIF image, rather than the usual TeX dvi. And mimetex is an entirely separate little program that doesn't use TeX or its fonts in any way.
TODO: put some examples here... used to be a bunch, but all have 404'ed away
AM (14 may 2007) I like that!