I'm a member of
lolhistory, which is a community themed around history macros. Much of it relies on the kind of jokes that only pure history-dorks love (a Mesopotamian carving captioned "Im in UR!", a 16th century still life of a table setting labelled "I can has cheese, burgher?").
i_iz_norml posted one on Socrates today, which I think is now my favorite one from that community:
I think that sums up most of the philosophy courses I've ever had to take.