"Ooze" is a creature type if you find a comprehensive list of monsters. If you want ooze-like monsters as well, Bloodrot (HoH 140) and Blood Amniote (LM 87) are undead, and I think there is a Bone Ooze or something similar as well. Offhand, in addition to the Monster Manuals you can find oozes in Sandstorm (Brine and Lava, 178) and Frostburn (White Pudding, 147). Looking up those page numbers just now tells me that you can try the Fiend Folio (3.0 but has an official conversion).