Senpay from Fallout Encyclopaedia managed to create a script that allows exporting 3D models from the Van Buren (original, canceled Fallout 3 by Black Isle Studios) tech demo into 3D Studio Max. Given the nature of the tech demo, some of them are just low-quality placeholders, but others can be quite useful for Fallout 2 modding (they're probably too low-res for Fallout 3). It's unclear how many exactly can be exported, but Vault-Tec Labs (our Fallout modding wiki) admin Dude101 estimates the number to be 500+. Some of them, like the creatures will probably soon end up at The Vault too. Here are some samples:
You can find more of them at No Mutants Allowed.