HMRC data
The UK government publishes lots of spending data now. Let's do cool stuff! ScraperWiki is one of these new-fangled cloud services, hosting code that scrapes websites. You can throw some python (or ruby, or php) together to download all the CSV files for a department. Google Refine is like a spreadsheet on crack, with features ideal for cleaning up messy data sets. I saw it for the first time at OpenTech 2011 a few weeks ago in London....