As GuitarRock brought to my attention on my talkpage, there are several pointless and unnecessary categories.
There are two steps that would be taken to stop this; standardizing categories and deleting old ones.
Standardizations are the tougher half; both in naming and with what exists. As for naming, I think it would be prudent to have names fully spelled out (e.g. My Little Pony Images rather than MLP images, hypothetically). Capitilizing all words in category names would also help.
As for which categories should or shouldn't exist, I'd like to hear everybody else's thoughts first. Should, for example, a "Rarity" category exist? A "Rarity Images" one? At what point do sub-categories become too dense to be useful?
Lastly, the cleanup of old, outside-of-standardization categories. Ones not adhering to new naming conventions would need to be renamed by an admin, and ones that shouldn't exist would be deleted.
Thank you for any thoughts on this matter.