Heat maps are usually used for click tracking on the web nowadays, and not much more really. The reason for that is mainly due to lack of statistics, organisations are usually very up tight about the data they give out to the public, however a game development company i've been working with has taken the opposite view. They are releasing as many stats as possible for their game, from all the items you buy, to every kill you make; but not just that you killed someone, but where you killed them.
So combine the location of kills, a static map, and you end up with lovely things like this...
This image is comprised from 2,458 banning draft games, where the average PSR of the game was above 1,750, and within all those games a total of 141,284 kills were recorded. Many thanks to S2Games for providing the data that made it possible to create this image.