Well, no need for a free look camera. Basically I'm inspired by isometric pixel art, Theme Hospital style. I'd like to be able to view the world from 4 different fixed angles, e.g. SimCity, TheSims. But I'd also like to have the freedom of a GTA game (driving, fighting). Movement and level design without the restriction of a grid, yet still not true 3D.
To answer your question, I haven't looked very far, I'm just starting some research into a recent idea for my first proper game. Just typed "like Fallout".