If you appreciate or program in OpenGL to any degree, you owe it to yourself and the HAIKU community to check this stuff out:
SMASH:
http://www.cgl.uwaterloo.ca/Projects/rendering/Papers/smash.pdf
OpenRT:
http://www.openrt.de/Publications/TheOpenRTAPI_OpenSG2003.pdf
These are “Next-Gen” API development documents in .pdf format, I hope you’ll take some time to read through them, as they’re very informative.
Please, feel free to post anything such as what I’ve included here for any prospective API implementable on HAIKU.