Huffington Post has created a very useful visual and statistical tool for keeping tabs on the evolution of the 2012 presidential race. This website features a map color-coded to show strong, moderate, or undecided support for Barack Obama or Mitt Romney. If you place your cursor over a given state, the respective percentages of support or that state pop up. That information can also be found in a comprehensive table further down the page.
If the election were held today, President Obama would win re-election by 316 electoral votes to Romney's 206. When you glance at the map, that balance seems counter-intuitive, because there appear to be many more red (Republican-leaning) states than blue (Democrat-leaning) states. The explanation, of course, is that under the electoral college system, votes are decided according to population, not area. A few states with more voters can carry the election over more states with fewer voters.
To see this in operation, at the linked website look closely at the upper right corner of the map. You'll see a tab marked "Geographic" (the map you're viewing), and another tab labelled "Cartogram". Click on the second tab, and voila, you're presented with a cluster of color-coded circles whose size corresponds to the number of electoral votes wielded by that state. Suddenly it becomes clear which states are key to winning the election ~ the larger circles. And it also becomes clear that there are (currently) more large circles that are blue, than red. Hence Obama's lead.
(A different kind of cartogram would distort the size of each state in proportion to its electoral clout. The image above is an example, showing the electoral results by state in the 2008 presidential election.)
An additional handy feature at the linked website lies at the lower right of the map/cartogram ~ a visual depiction of half a dozen states which have recently shifted their political alignment. The trend toward or away from strong support for either side is important to track, as we near election day. Thanks to HuffPost for this service to the electorate.