Secondly, some of the offered genres are too close to each other to choose properly even for an edm nerd: the very first choice was between minimal house and deep house, with a rather bassy-dreamy track. This can be solved by marking similar genres one time in the database. Then, a higher difficulty setting could exist for hardcore geeks, presenting choices from neighboring genres.
Finally, it would be nice if the samples were of similar volume level, so I don't have to fiddle with it on my computer. Since the samples are short, you could analyze the volume on the fly with ReplayGain or a similar algorithm, and apply a correcting gain accordingly.