tweetminster
More power to the argument that 2009 is going to be the year that twitter really breaks.
Tweetminster is a service that lists all UK MP's who are using Twitter and their twitter id. Following on from the official Downing St twitter feed and social media makeover now you can find and follow your local MP (if they tweet, it's still in the early stages so low on numbers) or some of the bigger names like C*meron*spit* are also on there. Check it out at tweetminster.co.uk.