Main sample libraries formats that can be used on Mac Os 9:

Kontakt: versions 1.x, 1.5 and 1.5.2
Kompakt up to version 1.0.3
HALion: versions 1.x, 2.0 and  2.0.3
Sampletank up to version 1 and 2?
EXS versions MKI and MK2 (up to Logic Audio 7.0)
MachFive up to version 1.2?
Gigasampler versions 1 and 2.
Soundfont versions 1 and 2. But no SFZ

AKAI CDs...

And any kind of wave or aiff loop file...