NES CHR Editor
A small editor to edit NES character ROMs; mainly knocked up so I could add some pointless graphics to the NES CASM example code.
NOTE: It won't edit NES Game ROM graphics -- the idea of this tool is for developing graphics for your own code.
Completely undocumented, but the NES has very basic graphics, so it should be self-explanatory.
Sources are available here.
A pre-built binary is available here which requires .NET to run.