I am new to this site, and am using it for music for a current project. That said, thus far, I find the search capabilities to be shockingly limited, and trying to find anything specific is an infuriating experience. Some relatively simple changes would make this infinitely easier.
Most importantly, keywords need to be replaced with more specific criteria. Genre, mood, instrumentation, and tempo should all be separate search criteria. It should also be possible to search based on whether or not the piece of music is subject to performing rights royalties (PRO), and whether it was recording using real or sampled/synthesized instruments (or a combination of the two).