GitHub tracks the number of downloads for all assets (files) that are attached to a release, but GitHub currently makes it very hard for users to get at this information. The number of downloads is currently only accessible through the API.
I noticed this many months ago when wondering how many people were downloading the new C++ version of Huggle. At the time I started coming up with some odd little script that I could set running somewhere checking the download counts and updating a static list, I even thought about just uploading the build files to some other site that tracked this information.
A few days ago I took my first look at developing chrome extensions for a referencing tool for Wikidata, and thus today I thought, why not just make an extension for chrome that adds the download counts to the GitHub releases page!