Congratulations on starting up this site: it promises to be a valuable resource for everyone interested in GIS, whether they are formally involved in teaching (and learning) or not.
Web-based Q&A sites have been developing and growing a lot over the last decade, beginning with vendor sites like the ESRI forums but now including independent sites like the StackExchange-GIS site that first attracted my attention over two years ago. (Example: http://gis.stackexchange.com/q/12105/664). Most are useful; some can be addictive; but none is perfect. I think a common struggle is to be accessible and meaningful to what is an incredibly diverse community. (About the only thing users of these sites have in common is GIS. Their applications, backgrounds, skills, interests, cultures, and languages span the widest possible spectra.) I am wondering, then, what your reactions to such sites have been; what opportunities you see for them; how they might fit in with the other teaching resources you link to and offer here; and how we should be thinking about using and improving them.