Making heat maps using ArcGIS?

Coincidentally, I have been doing a lot of reading about this subject over the last couple of days. For the actual generation of heat maps there are a large number of factors to consider.

The most valuable resources for me were from Laura Rosenshein at Esri. She sums up a lot of the material in this one blog post.

To answer your question, I would recommend watching the videos linked on that page and then running through the tutorial - that gave me sufficient knowledge on how to use the Spatial Statistics tools in ArcMap to create a multi scale-level heat map for my web application.

If you are short on time, this post gives a good summary on considerations to think about when creating a heat map.

It might also be worth checking out this library which is hosted on the new ESRI github. The library allows you to make a heat map on the client side using HTML5.

A demo of the application: http://esri.github.io/heatmap-layer-js/

The github site: https://github.com/Esri/heatmap-layer-js