Online Tunable Receivers
United States:
Reston, VA (the original!)
N2JEU (Canastota, NY)
W7DXX remote base (Las Cruces, NM)
N3FI (Hughesville, MD)
Ham Lake, MN (I like this one!)
Live ham radio from Dallas, TX-3819 kHz (this one is interesting, although cannot be remote controlled)
Outside the US:
List of several online remote-controlled receivers around the world
VR2HF (Kowloon, Hong Kong)
JR6NJD (Web receiver in Beppu, Oita, Japan)
Web receivers in the United Kingdom
HB9AFZ/HB9TC (Switzerland; only available on weekends from 0800-2000 UTC)