First let me say very nice idea implemented into a module! Hadn't known about this php library before, and stumbling across this module made implementing it a snap. :)
One possible idea/request though....
Currently we have:
 All pages
 Non-admin pages
 Admin pages
 Home page
In the admin section, to decide which pages should be 'tracked', as it were... My question is, would it be possible to open this up a bit? Maybe even a freeflow similar to how with blocks in core, we get:
Show block on specific pages:
 Show on every page except the listed pages.
 Show on only the listed pages.
 Show if the following PHP code returns TRUE (PHP-mode, experts only).
Of course, I don't have enough data yet to know if this is going to be a problem, but I've noticed that at the rate I'm going, I'm going to end up with hundreds, possibly thousands of "Groups" listed, as we use Drupal as both a CMS, CRM system, and a dozen other things (we have invoice management, client management, billling, affiliates, etc, all wrapped up neatly in Drupal by the time this project is done), so there's thousands of possible urls going to be involved... If we could do a "Use on every page except those listed" and then list out wildcards such as:
... etc ...
It would probably cut down on "unique" urls that really arent worth tracking anyway (as they wont get but a click or two ever logged to them)... I'm not familiar enough yet with clickheat to know if this is even going to be scalability problem. (I suppose if it's not, I can just ignore all those options in the dropdown when viewing the reports..ehehe)
Just an idea.. if it's too far out there, or just something you dont have time to play with in the near future, I'd be willing to take a look at the code and see what I could patch up, but right now I'm hip deep migrating all the aforementioned internal modules to Drupal6, so it would be a while. :)