AoPS itself certainly has some interesting such courses, e.g. Counting & Probability and Number Theory, but if someone had courses on set theory, logic, graph theory, etc., then we'd be interested in those too.
DS quite likes the Barwise & Etchemendy "Language, Proof and Logic" book+CD course - he's done more playing around with the software than systematically going through the book, but that's OK in this case. I would love to recommend you a certain recreational book on logic, sets and proof theory (no, not mine!) but it isn't ready yet. Graph theory's a big hole in the market, it seems to me. Gertrude, Superperson and the Monster (
http://www.ccs3.lanl.gov/mega-math/workbk/graph/grgsm.html ) were a noble start, but it's a pity about the bugs, and besides it's died.
