To simplify the search for high quality sounds it would be very good if the rating of that sound is listed in the list besides downloads / commentss.
Interesting idea. Also an option to sort downloads by best rated. Right now you can sort by popularity in terms of number of downloads, though.
I think that a rating based on "number of downloads per day" would be useful.
At the moment, sounds that have been on the site for a long time, benefit from the number of downloads figure. But a new sound may come along in the same category, which is better, and this may well be indicated by the fact that it is currently receiving more downloads per day.
Admittedly this may slightly favour new sounds, as a few stalwarts d/l almost anything new in the first few days after submission ... perhaps some compensating factor could be included in the equation.
It's a tough nut to crack for sure. I'd like to see how sites like flickr calculate "interestingness", I think it has to do with the amount of activity surrounding an item (views/downloads/comments/tags/ratings) over time.