Can you define "better"? Do you mean "more extensive" or
"nicer-looking"?
I'm not sure I know any more extensive set than Computer Modern with
the American Math Society extras, and these have all been available in
the public domain as Type 1 for some time (as well as being available
as a commercial product), and I think the TrueType versions are being
worked on.
The only serious alternatives are the MathTimes add-ons to Times New
Roman, and Lucida Math, both of which are commercial products, as far
as I am aware, and unlikely to be made available for free (see
discussions with Chuck Bigelow on TYPO-L, _passim_).
I fully agree there should be more comprehensive math fonts, but
someone's going to have to fund a type designer for a couple of years.
///Peter