Interesting demo, I did a similar one but with mouse movement: <a href="http://www.patrick-wied.at/projects/multiuser-heatmap/" rel="nofollow">http://www.patrick-wied.at/projects/multiuser-heatmap/</a> but I think my server wont handle lots of users since I'm using an early version of Ajax Push Engine. nowjs seems to perform really good.<p>Btw: nice solution for the "too much data" for heatmap.js (at the initial heatmap rendering) issue :)
Quick notes:<p>When there is a lot of realtime clicking it'll get laggy because the heatmap redraws with new data. Sorry about that!<p>If the page in the Iframe has some kind of redirect, it'll redirect the entire page so just wait 60 seconds for the page to change.<p>Other than that, have fun!
I couldn't figure out what the link was at first, because in Safari, absolutely nothing happens. I had to bring up the page in Chrome to see what it was supposed to be doing (heat marks).