An archive of the excellent SuperColdMilk site is now available.
If you've not come across this site before, it's a great resource full of useful AC3D plugins (some which have already been incorporated into AC3D). There are also tutorials. If you are interested in developing with AC3D, many of the plugins include downloadable source code. (Licensed users can contact us via the main web site the for SDK header files)
Check it out:
http://www.inivis.com/supercoldmilk.html