I never actually tried one of these click visualizers although they have been around for a while, installed one an hour ago on my Ex Girlfriend Revenge site Revengetv.com, check out the screenshot:
Notice all the clicks are pretty much where you'd expect it except for the one greener dot in the text area (second paragraph on the top rightish). Well it was a typo of "theres" instead of "there's", and the surfers constantly clicked on the thing.. So that tells me if I want some link to get more clicks, simply misspell it lol!!
Seriously, this tool is great for figuring out which thumb surfers like most in a multi thumb graphic, seeing what areas of your free site the surfers don't go near or love.
it's free and easy to install:
http://www.labsmedia.com/clickheat/index.html
there's more advanced verison that cost money, but the free version does pretty good for me.