For graphics, I like to work on original games rather than remakes. But background/tiles, sprites, anything really.
I've always been into game design so I like to plan the games, along with the programmer.
I usually try to come up with ways to improve and deepen the usual style of side-scroller/shooter/Puzzler.
The thing I'm thinking about right now would be a platformer/side-scroller like flashback
or another world but simpler, and do it in a zombie/exploring setting. I'm not sure what the graphical style would be, but I like to keep it simple, but with an distinct (here: eerie) feeling.
Another Idea: A game engine similar to the one-screen level games (rainbow islands, rick D) but with an occult/Lovecraft theme. Simple enough graphics and gameplay but with twists and traps and such. Maybe the player would work his way down through the netherworld to face demons...
For smaller games, graphics aren't that time-demanding. It's the programmer who usually have a hard time to do the code in his spare time. If any of these sounds interesting, let me hear from you. I find it the easiest way to pitch game ideas and then we work out details later.