The main text font for this site is Gentium Plus (which does not include glyphs for Hebrew). We also include Linux Libertine, Brill, and Charis SIL in our font stack, so if you have any of these fonts installed on your system, all should be well.
Gentium Plus (see above) includes a full and attractive set of Greek characters. We also make use of SBL Greek, and Palatino Linotype which is pre-installed on many Windows systems.
SAHD articles make limited use of Syriac; currently the display font is set to Estrangelo Edessa, part of the Meltho Syriac Fonts project.