Flight Path UK, online aircraft tracking within the UK will be up and running within a couple of months.
http://212.240.135.5/
Well worth a look at the demo, although for £9.99 a month I am sure that after a month of interest you wouldn't spend more than that.
I am disappointed that the refresh rate is as much as two minutes, defeating the object of 'realtime tracking!'
However I do like the filters that can be applied to the aircraft. For example you could just show all aircraft going in and out of PIK doing 250 below 10(!)