Maybe we can just add useful links to this discussion as we find them and create a little link library? Add a URL and a brief description:
http://www.appropedia.org/Category:MOST - keep up with Dr. Pearce (if you can).
RepRap.org - the first place to go to for questions. They have a very active forum, too.
http://calculator.josefprusa.cz/ - a slick set of tools for calculating various settings. This guy's the pro who designed most of the printer you just built and he's pretty close to wrapping up the next version.
http://www.makerbot.com/blog/2011/01/19/openscad-basics-the-setup/ - this is a pretty good set of tutorials for OpenSCAD and along with the built-in examples will get you and your students going nicely. Also check the libraries folder in the OpenSCAD program directory as there are some unbelievably cool things you can use in your designs, like the ever-popular involute gear library.
http://cloud.netfabb.com/ - this is great for fixing stl files that just don't want to slice nicely. Cura has now built some of these features in (accessed via Expert Settings) but NetFabb is the master and almost always works.
http://www.numberfactory.com/nf%20metric%20screws%20and%20bolts.htm - this is a neat little database of metric fastener dimensions. There's lots of other really useful stuff at this site, too.