My first attempt was make highpoly models to bake, but it takes triple time to model and several hours testing and baking, until a "clean bake".
Luckly I found this
Infinity - Texture Kit 0.7
it is from "infinity" game community, all those scripts was made by a guy called "Space", he have other usefull stuff, but heres the one I'm talking
http://3d-output.com/spAce/files/spAce% ... 200.73.atn
to keep it simple, you draw the height map and click "play" on the script "bump to ao", and its done.
It generate a fake AO map, based on the relative height you set, isn't perfect, but is more than enough for gaming purpose, it works even better with flat surfaces, like plates, holes bolts etc.
see this example, together with Nvidia Normal Map plugin, you can achieve similar results, without the pain of highpoly bake.
![Image](http://img521.imageshack.us/img521/9127/aoplug.jpg)
hope it helps, and thanks to Space.