tags and filters
I propose a tagging feature that can also be used to filter in/out images.
We all love different things, but many "appropriate" images are either uninteresting, startling, or just damn annoying. Imgurites should be able to post their pokemon, Community, lolcats, spiders, Emma Watson, Minecraft, shock/horror gifs, whatever, but I think Imgur is getting popular enough that we can no longer generalize about the collective preference of the community. Especially with the new ability to directly upload to the feed, it would be really nice to automatically filter out the images that we definitely don't want to see. I think the community can be trusted to properly tag images and police tag abuse for the most part.
Customer support service by UserEcho
Furthermore, tags can help you better monetize non-pro users by understanding their preferences more than can be gleaned from just up/downvotes on particular images and comments.