There are a number of places online that offer free graphics for games. Many are not necessarily appropriate for NES games, but they can always be adapted to be smaller, use less colors or even just for inspiration.
http://opengameart.org/
Featuring cool stuff like this.
http://www.molotov.nu/?page=graphics
If you search specifically for free roguelike tilesets, these can be particularly useful - they're going to be tile based, small, and fairly simple most of the time. You could even use many monster graphics in sidescrollers or other games.
http://roguebasin.roguelikedevelopment. ... ical_tiles - has some dead links though
http://rltiles.sourceforge.net/
Feel free to post any resources you can find.
http://opengameart.org/
Featuring cool stuff like this.
http://www.molotov.nu/?page=graphics
If you search specifically for free roguelike tilesets, these can be particularly useful - they're going to be tile based, small, and fairly simple most of the time. You could even use many monster graphics in sidescrollers or other games.
http://roguebasin.roguelikedevelopment. ... ical_tiles - has some dead links though
http://rltiles.sourceforge.net/
Feel free to post any resources you can find.