A website tracking all mentions of GitHub repos on HackerNews and Reddit (almost in real-time). As a result of that, there are a lot of interesting stats that could be extracted.

For example:

Most popular repos per language: https://www.libhunt.com/lang/python

Similar and alternative projects: https://www.libhunt.com/repo/Signal-Android

Most popular programming languages: https://www.libhunt.com/index