FYI, unblock-us.com is a handy service that lets you easily switch between the different Netflix libraries (US, Canada and UK). It costs $5 per month and is well worth it!
I've seen unblock-us.com being recommended a lot. I signed up for it a couple days back to get my Burn Notice fix and it's definitely awesome. I went through the trial a month ago and found the streaming to be real crap (maybe I just went through it at a bad time) but after signing up for a month it's now great.
The US Netflix has so much great content (but we have all the cool BBC stuff here too).
It's not that content is blocked, each region has a distinct catalog based on what Netflix has licensed for that region. There is strong overlap, but all regions are unique.
(You only require one Netflix account).