I agree with Corey. History is my main subject. Weaponology is the next best favorite of mine. Man, the stuff we make nowadays!
Music, they have classes for ot.
History after the 1900 storm in Galveston. They raised the entire island fifteen feet is was an unbelievable project
German, love learning the history and of course how to speak the language :D
Learning about my next travel destination, which will be Maui come this October. (Just paid the balance off today for airfare and hotel.)
English Dark ages History. You can read about it and then go and look at it.
History of WWI & WWII & the Cold War. I love reading historical fiction and spy fiction about that era.
I'm fascinated by the imponderables, the questions for which there can be no answers -- the why? What? How? Of human life.
I suppose I could get just as much frustration wearing a hair shirt, but seeking answers to impossible questions is more fun.
Science stuff about the Human Body.
The natural world, and history.
Astronomy , it's an interesting subject which makes you never fall asleep when you read lol
Foreign languages :)