[Suicide Junkie]

Just to be clear, the imagepacks have absolutely no effect, visually or gameplay wise.

They only actually have an effect when you run mods that ask for these extra images.
The point being to save you time downloading the mods (since you don't have to download the same graphics for P&N, and Adamant, and MGM, over and over)
It also saves space on your harddrive since you don't have multiple copies of those bitmaps.

And as a bonus, it makes it easier for modders to include fancy images in their mods, since they have a large collection to choose from.