You know what would be great? If people who've purchased rights to an asset had the ability to review it - with a star system and/or a comment. Especially since the only preview you can see on most stock is a fairly small, low res image.
Add to that, if there were a way to exclude a particular contributor from search results, it would help a lot with working past the ones that like to spam search terms with hundreds of almost identical images.
Also, for that matter, simple Boolean operators on keywords would be awesome. Like car+road+driving -truck -pickup
Also also? MAKE contributors who've 'shopped up the image list "photo illustration" or "manipulated" or whatever the decided term would be as a keyword. It would be awesome to be able to remove thousands of results where someone had added a buzzword or some arty effect. I know it'd be damned near impossible to do this retroactively, but dang, it'd be nice.
And, of course, that calls to mind isolated / cut out images - there should be a standard keyword (I think the software uses "isolated" but a cabin in the woods can be isolated, too) and it should be required.
I don't ask much, do I? But, time is money... And the more you can help me cull spam and results I can't use from my search results, the faster I can get back to work, and the more you become my preferred service / first stop for everything.