Music For Phreaks - http://www.musicforphreaks.com/
I often play on the Fushion Sound System. My mate Julz runs it, and it's as good a sound as you'll find. He also runs a Deep House night in Reading called Music For Phreaks.
Wellcoolstuff -
http://www.wellcoolstuff.com
These guys are friends of mine from Reading, and sell everything from mix tapes to t-shirts to bongs. They're a headshop online and well worth a visit.
Poleshift -
http://www.poleshift.net/
As a Poleshift DJ, it's right that I should include this link. The Poleshift DJs cover a vast array of Dance genres, from Gabba to Hard House, and Psy-Trance to Disco. Ting, the girl who runs Poleshift is a very special person, and a great friend of mine.