Either in Kazaa Lite or LimeWire, type "Bass Test" as the song title. You will get pleny of hits. Some will give you a range of frequency starting from 320Hz to 10Hz, while others will just pound the lights out of your subs.
Out of everything I've seen, I still have yet to see DJ Magic Mike 'Drop the Bass'. Or 30's and Low's. Are they still around, or am I beginning to show my age?