How powerful is your vote? There's now a new website which can tell you.
In the 2005 election, more than half of all voters voted against their winning MP. There were an estimated 25 million wasted votes, which were 'thrown away'.
In the absence of a proportional voting system, in the UK, the voters with real power to choose the government are those who live in marginal constituencies, and these are who the main parties and media focus on.