shame you have to sign up though! I use to use gamespot.com which also requires you to signup! but dont usualy download demos! last one was the PES3 demo for the PC!
You do have to sign up, and you have 100k max download speeds (unless you susbcribe, which I don't see the point in doing for the amount of demos I play)
www.3dgamers.com where i go, sometimes the servers are full, but if you check back about an hour later they pretty much clear up, i download files from them about 400-600mb/sec just depends what my brother is up to on his comp!