Depends on what shows you are looking for. I get more than enough shows with the combination of BBC, ITV, Channel4 and the Swiss channles (with dual/original language). For eg:

Heroes: BBC 2 or HD - only about 10 days behind the US.

Desperate Housewives: Channel 4 - only about 3 weeks behind the US.

Lost: TSR1 - started showing season 4 about 3 months later than the US, but by transmitting 2 or 3 episodes in a row each week, the season finale was barely a month after the US.

One Tree Hill: I think they just finished season 5 on TSR. (aired in the US in until May 2008)

Prison Break: on TSR, season 3 was only 2 months after the US.

Gossip Girl: Season 1 was on ITV (or channel 4?) last summer. Season 2 should be coming soon.

CSI: too many times during the week.. I can't keep track anymore.

House MD: TSR1 has finished showing season 4 last autumn. (currently season 5 in the US.) Season 5 should be here in the summer.

Comedies are a bit more difficult. They tend to show daily reruns...

It is hard to tell when the shows are coming - In general, the UK channels are the quickest but you don't get a lot of choice. Then TSR should show the shows about 6 months after the US, and SF2 will follow about 6 months after TSR... I would record whole seasons (as you can with Bluewin) and find myself with plenty to watch spread out over the year.