In an effort to get this thread moving again, I started going through the 2E Mystara MC. I wrote up brief descriptions of creatures I'd like to convert for those who are unfamiliar with them:
Actaeon: 11 HD, N - elk centaur, breath weapon turns victims into animals, summons woodland creatures,
Agarat: 4 HD, CE - ghoul-like undead, has energy draining scream
Ash Crawler: 3 HD, N - burrowing fire creature with clamping jaws
Baldandar: 6 HD, NE - shapeshifting humanoids with a poisonous bite and magic
Bhut: 7 HD, LE - shapeshifting humanoids with a numbing bite
Coltpixy: 3 HD, CN - unicorn-like pony
Crone of Chaos: 6 HD, CE - relative of the hag that controls animals
Darkhood: 13 HD, NE - undead that feeds on fear
Darkwing: 3 HD, NE - flying humanoids that hunt at night
If you're looking for more info on each of these, there are 3.0 conversions at the
Vaults of Pandius