One of the more pleasant surprises in computer technolofy is when a long-standing project under development comes to fruition as a usable product. Such is the case with the STIX Fonts, a set of OTF fonts released under the SIL Open Font License, which is an open source license.
The focus of the STIX fonts are math and technical symbols, and there are plenty of those in the font set (at the appropriate Unicode points of course). However the fonts also include a variety of Latin, Greek and Cyrillic characters and even some phonetic characters (which is nice for linguistic publications referencing logic and set notation). The typographic design is based on Times New Roman, a common font used in many technical publications. STIX is also designed to be used in MathML.
There are other math freeware fonts, but the STIX family is notable for 1) including a variety of predesigned fonts for bold, italic and multiple font sizes and 2) being sponsored a consortium of scientific societies including the American Institute of Physics, American Chemical Society, American Mathematical Society, IEEE (Institute of Electrical and Electronics Engineers), American Physical Society and Elsevier.
Version 1.0 includes basic support, but future versions are scheduled to include additional support for Microsoft Word and LaTex.