Try
www.satco.org or their uk branch
www.satuk.org.uk This is a real-time ATC simulation network which brings together Controllers (via the 'ProController' software) and Pilots (via the 'Squawkbox' plug-in to Microsoft Flight Simulator 98/2000).
ATC-Pilot communication is either by text or often by voice using 'Roger Wilco' RT simulator software, and the experience is very realistic.
All the software required to take part is free (except for MS Flight Simultator for pilots), it's great fun and the aim of the guys involved is to stick as close to real world practice as is possible. And just like in the real world the London-based controllers are considered amongst the most professional in the world. There are even a few real-life LATCC controllers and professional pilots involved for whom it must be a bit of busman's holiday.
A few weeks ago the virtual London ACC had a 4-hour fly-in with 22 controllers online in the London TMA / London Airports, c. 400 flights through the London ACC and EGLL achieving 40 landings per hour.
You'll often find me on there controlling as Thames Radar 132.7, or flying as BRT7617 (J41) or BAW907U (B752), as a bit of fun in between real-life ATPL studies...