Every year since 1995, the nonprofit organization Transparency International has been publishing a "Corruption Perceptions Index" where countries are ranked--based on data from a several surveys and assessments--from 0 to 100, "0" being "totally corrupt" and 100 being "totally clean."
The group just released their 2012 data, along with several graphics. Among the interactives, which you can find on the organization's website, my favorite is this interactive wheel--I think it's the cleanest and sharpest way to see how one country compares to the rest of the world. This mouse-over map is nice too.
There are also a couple good static graphics. Check out this first one for a quick look at the way the U.S. stacks up against the other G-20 countries:
And a version with all the world's countries.
This graphic makes me curious about how corruption (or perceived corruption) has changed in the U.S. over the last couple of decades...look out for a chart answering that question soon.