What American shows AREN'T popular in the UK is a better question....
Right now we have: Smallville, The OC, Americas Next Top Model,American Idol, One Tree Hill, Friends, Thrid Rock, Futurama, Family Guy, Simpsons, ER, The Apprentice, CSI, West Wing, Will and Grace, 24, Despeerate Housewives, Invasion, Alias, Charmed, Shipwrecked, Knight Rider, Roseanne, The A Team, Planets Funnist Animals, COPS, Malcolm in the Middle: Nip/Tuck, Law and Order, Brat Camp, Punkd, Meet the Barkers, Pimp my Ride, Wife Swap, Cheers, Wonder Years, Bold and the Beautiful, Quantum Leap... you get the idea
We get most if the same TV here as you do there. It is the wonder of Cable/Sattelite... But even on regular TV we get a ton of US shows as well as British stuff...