Unicode 3.2, released in March 2002, included 4 scripts not currently part of OS X. Here is the status of their usability on the Mac as far as I know. Where there is a font but no keyboards, characters can of course still be entered directly using the Character Palette.
Fonts: Baybayin Lopez, Bikol Mintz, Bisaya Hervas, Fixedsys Excelsior, Tagalog Doctrina 1593, Tagalog Stylized
Fonts: MPH 2B Damase
Fonts: Tagbanwa Font