Re: 1 on 1 D&D 3.5 Game
Oslecamo is a well known poster on the MinMax Boards (Formerly the Giant in the Playground).
He has put a lot of work into adapting 3.5 monsters into racial classes in the same flavor as Savage Species did. No LA or Racial HD. However, there are differences but I'm not sure I could explain them off the top of my head.
He has also gotten a number of people into doing the same work, and this comes with people creating monster PrCs (from Doppelganger to Greater Doppelganger up to Ethereal Doppelganger, Kython PrCs, Greater Shadow) Templates (Swarmshifter, Shadow Creature, Titanic Creature, Paragon, Legendary Creature) and even specialized feats for monsters (Deepspawn being able to create Outsiders or Elementals for example) or more general feats like Deceivingly Innocent Form, which lets any monster masquerade about as a mostly human version of themselves.
You can find it all under Oslecamo's Improved Monster Classes on the MinMax Boards.