Maledonna! That series really needs some new content UvU As for fan art, I'm thinking ATLA and LOK, SPN, Doctor Who, and Pokemon! And I think I remember reading somewhere that you CAN sell Homestuck art if you get permission from Hussie. But if not, you could always make chibi stickers or bookmarks and give them away with orders over certain amounts.
You should do a little chibi set of mlp as humans! A marceline-PB print or a Prince gumball-marshall lee labulabu pic. More Sailor mooon cuz the new show is coming out and maybe a sexy Rei,Asuka,Mari pic from the new movies?