These are some suggested fonts for use with SWORD tools. Any of these work with either Linux or Windows tools, and probably Macs as well, though certain fonts work better with different tools. They're TrueType fonts, which means that usually just copying *.ttf to the right place makes them available, and that's necessary only if you don't have some sort of package manager or font installer to do it for you.
GNU FreeFont, consisting of serif, sans serif, and monospaced typefaces in regular, bold, italic, and bold italic fonts, is an attractive set of open source fonts covering a broad range of scripts in the first two Unicode planes. Many of the glyphs incorporated into FreeFont were designed by professional type foundries.
- A derivative of the above Free Serif typeface, FreeIdgSerif, was designed for Indo-Eurpoeanists, but has wide character coverage of use to Bible users.
Linux Libertine is a very pretty typeface that provides quality character sets for all of Latin, Hebrew, and Greek, which makes it especially useful for commentaries that use all three. While it is designed for Linux, it works quite well under Windows, as a display typeface for SWORD tools.
There is quite a selection of other fonts available from SIL. Visit SIL and look around, but the Charis SIL and Doulos SIL typefaces, in particular were designed with fairly broad coverage in mind.
For particular requirements on languages not listed here, it is generally useful to visit the Wikipedia page for the relevant alphabet or script.
"Gentium" is a good font for Greek. Look in repositories for gentium-fonts-1.02-5.fc7.noarch.rpm or go instead to  to get the *.zip.
"Ezra SIL" is SIL's best font for Hebrew and works very well in most SWORD front-ends. 
For BibleTime, the best Hebrew fonts are the Culmus fonts, particularly the Frank Ruehl CLM or Drugulin CLM. Many Linux distributions have a Culmus fonts package (Mandriva calls it fonts-type1-hebrew). If your distribution doesn't have this package, you may check out the Culmus Project site  and follow this link  to a truetype download.
See also Hebrew Support for Your Browser at the Mechon Mamre website. For front-ends that use a browser (or browser engine) to display Bible text (e.g. FireBible), this may be relevant if you have a problem displaying Hebrew vowels and/or cantillation marks.
For Vietnamese, fonts like Arial and Linux Libertine work well. However, the UVN fonts are excellent options that are designed for Vietnamese and can be downloaded for free. They can be used for English or other languages that use a Latin alphabet. UVN Saigon looks particularly good with many SWORD front-ends. You can find these fonts at the TTi website .
Apart from MS Arial, which is mentioned above as a good all round font, the prettiest free font is probably Nazli, available from Farsiweb and part of many Linux repositories.
Coptic is the final stage of the Egyptian language, a northern Afro-Asiatic language spoken in Egypt until at least the seventeenth century. Several Unicode fonts include coverage of Coptic. New Athena Unicode is one of them. For further Coptic Unicode resources, see  and .
The TrueType font AmazighU_Arial is a Unicode font that supports the Kabyle alphabet. However, this is a copyrighted font, made by the Monotype Corporation.
- BarahaPad – Text Editor for Indian languages
- BarahaIME – Input Method Editor for Indian languages
- Baraha TrueType Fonts for various Indian languages (released under GPL)
- A Unicode OpenType font called Tibetan Machine Uni is available under GPL license.
- A Unicode OpenType font called Sambhota Ededris is well advanced in development, though at present it is not available for public purchase. 
With only 0.01 people per square kilometer of land, Nunavut is one of the least populated regions in the world. And yet it has four official languages: English, French, Inuktitut and Inuinnaqtun. For this reason, the government of Nunavut adopted a clean sans-serif font called Pigiarniq (designed by Tiro Typeworks) that enables its people to use all four languages in a uniform manner. The result is a professional-looking free font family. 
Other nice fonts with wide character coverage require purchase or registration. These are not endorsed by CrossWire, though some of us certainly use them.
TITUS Cyberbit Unicode (requires registration to download, otherwise free) -- 36161 codepoints, designed for Indo-Europeanists & medievalists.
Code2000 (free to try, $5 to register if you can afford it) -- aims at complete coverage of the Unicode Basic Multilingual Plane (BMP) aka Plane 0. Also available from this page are the freeware fonts Code2001 and Code2002, which are Plane 1 and Plane 2 fonts, respectively.
ALPHABETUM (limited trial font which is missing glyphs, €15 to purchase full font) -- a good font for a number of ancient languages such as Gothic, Old Church Slavonic (incl. Glagolitic), Ugaritic, & Phoenician
- Alan Wood’s Unicode Resources – Unicode and Multilingual Support in HTML, Fonts, Web Browsers and Other Applications
- Got Unicode? – Elizabeth Pyatt's Unicode tips, resources and war stories.