[Suicide Junkie]

For graphics, make use of the imagemodpacks.

You don't include them with your mod, but simply mention which ones are needed.

The packs are designed to fit over top of the stock pictures files, so they are installed just once, and become available to every mod.
In addition, most people already have the latest versions installed.

More pictures than you can shake a stick at, and it dosen't change your mod's download size or install size.