A quick trip around the net revealed the following resources for royalty free game graphics you can use in your projects:
I'm sure there's loads more out there, but this should be a good start.
In other news, my experiments with gosu have so far resulted in a small library that strives to make building games even easier, offering simple actor (sprites, etc.) management with pluggable behaviours. If this thing gets to a point where it's actually useful, I'll put it up on github.
opensource: del.icio.us tag/opensource
sourceforge
tool
graphics
3D
free
download
opensource
gamedev
modeler
opensource: del.icio.us tag/opensource
graphics
virtual
visualization
3D
openGL
free
download
opensource
gamedev