While I have attended many genealogy classes and seminars on a great many topics, by outstanding speakers, my favorite topics always end up being on maps. I think I majored in the wrong discipline, I should have went with a geography degree!
I had a series of Wordless Wednesday posts on a group of caricature maps I found and fell in love with. I also enjoy the David Rumsey Historical Map Collection as well as the panoramic map collections available online. If you have some time, actually a lot of time, visit some of the map collection sites you can find through Google, Cyndi's List or at the GHLL site, you won't be disappointed.