Psion
Adventurer
jaerdaph said:In addition to the others mentioned, I think Fantasy Flight Games and Necromancer Games do a clear and concise job of it.
I don't think FFG is especially exemplary. They use that dreaded "derived from the SRD" statement, which I HATE HATE HATE.
A good example not a lot of people are mentioning is AEG. AEG states both the details and their intent. The spell out chapters and sections, and put a statement that it is their express intent that all classes, skills, feats, spells, et al., are OGC.