Last night was deadmau5. The guy is in a mouse-head getup, with neon lights.
Have to say, it might not be everyone's crowd, but good techno DJ's tend to have a good sound crew and thunderously awesome sound equipment following them. Nothing like feeling pant-shaking bass complimented by the sounds of undistorted, clean, electronic wizardry.
The ear-numbing sound was actually a lot less fatiguing than you would think. I've been at rock concerts that were louder, but with poor speakers and poorer amplification, so your ears are constantly assaulted by distortion. Then when you leave the concert hall, it sounds like you're underwater. Not so here.
In any case, so goes my saying (for music listening in any situtaion): "Great music, when played loud enough, can cauterize the ears. On good days, also the mind."
The light show was certainly a trip in itself, here's some pictures: