When you head for the polling booth tweet #ukvote along with the first half of your postcode (for example, #ukvote SE1) and we will plot turnout in real time on a map. We're not asking you to include who you're voting for -- that's a secret you don't need to share.
The goal of the experiment is to inspire more people to vote and to help get a sense of turnout (on Twitter, at least) during the course of the day and across the country. You can see the results in real-time over at Tweetminster.
The experiment is inspired by a similar initiative around the hashtag #uksnow.