Here are a bunch of hand painted textures for a very old, UN-realeased game.
Some of the floor textures would be good in a top-down game, while the wall textures would be really useful or a Side-scroller.
Even if you do not use them, they are neat to look at and admire. He does seamless textures with paint and canvas rather than a image editor and computer.
I go there when I need ideas sometimes.