I found this today, and it's making me wish I'd installed WordPress on a server of my own instead of going with Blogger. Down the line I may have to change that, but in the meantime, there's no reason other people shouldn't be having fun with this:

http://www.labsmedia.com/clickheat/index.html

Looks like a neat thing, but I'm not sure it would reveal any new or interesting information as far as where users click.

For example, it might show a heat zone for the left column of my blog, but that's where the menu and recent comments are...that wouldn't exactly tell me anything I didn't already suspect.