An interesting site that XV277 posted a link to. One thing to be aware of though. Some of the pictures supplies by Microsoft Virtual Earth are seriously out of date. Even more so when compared to Google Earth (which I reckon is about 2 to 4 years old)
So far I have spotted
Old Warden - 2 hangars short and no runway extension (5 years+)
Duxford - No Area 51 by the M11
Brize Norton - VC-10 K.2s on the ramp
Cottesmore - No aircraft and the Harrier Ramp still half built.
Benson - Bulldogs on the ramp
My House - No extension (at least 5 years ago)
I need to get out more