Paul Kedrosky finds this link between unpaid tickets by a country's UN reps and corruption.
Let me propose a few more indices:
Number of lobbyists per politician (US would lead)
Number of hangers-on per politician (India would be high up)
Amount of budget directly influenced by a government official (China)
Amount of foreign aid which shows up in individual Swiss bank accounts (various African countries)
Transparency International does periodic surveys of perception of corruption. According to the 2005 survey, Iceland is perceived to be the world's least corrupt country, and Bangladesh and Chad are perceived to be the most corrupt. It draws on surveys of businesspeople and country analysts.
The US is ranked 17th, China 77th, India 88th in that survey.
Mark Twain once said the US "is a nation without a distinct criminal class with possible exception of Congress". I am pretty sure you could easily substitute US and Congress in most countries around the world and come up with the same conclusion. You just have to be ready with bribes, graft, bakshish, payola, dash, cadeaus, mordida, tea money, lap dances, soft money...