If you go over to http://www.simsig.co.uk you'll see that SimSig is now completely free. A couple of days earlier than planned, but I doubt anybody minding!
For those of you that don't know, SimSig is a simulation of UK signalboxes and currently has 6 simulations - Westbury, Stafford, Waterloo, Liverpool Street, Didcot, and Swindon.