While the "Where Does My Money Go" project, initiated a few years ago, might already be well-known for some readers, it is still useful to note it is regularly updated with some new visualization techniques.
In particular, Gregor Aisch, graphic designer and visualisation architect and known from projects like Europe's Energy and Plagiarism in the PhD thesis of a German politician, has been busy fine-tuning the radial bubble chart technique, of whicjhthe 'old' version is stil used in the Where Does My Money Go website.
Based on some early sketches by McCandless, the new hierarchical graph technique shows displays a collection of tree datasets in a radial layout with budget items represented as bubbles. The bubbles can be navigated horizontally, feature miniature ring chart depictions, while data is shown relatively to regional population size in an accompanying geographical map. Several implementations already exist: one that shows the regional spending in UK [driven-by-data.net] and one that focuses on the spending by the city of Berlin
More information about the new technique is available at the OKFN blog.