More info about a couple of the above follow; the rest have their own pages.
Since I prefer to work with git, and developing new features with git on separate branches is much more convenient than working with Subversion, I am running a git–svn mirror of the whole TeX Live Subversion repository. It is updated every 15 minutes.
There are git branches matching the Subversion branches, and also some dev/ branches where I am working on new features. The git repository carries, similar to Subversion, the full history back to our switch from Perforce to Subversion in 2005. This repository is quite large, so don't do a casual checkout—the size is currently around to 40GB.
We also (at irregular intervals) compute some statistics of this repository using gitstats. Don't take them too seriously.
Incidentally, the TeX Live repository on github contains only the relatively small tree of source files that get compiled (Build/), not any of the runtime files (Master/), due to github limitations.
A git repository of CTAN, updated with one commit per day. Large archive files (.tgz, .zip, etc.) are omitted. Perhaps CTAN will provide its own repository in the future, in which case this will no longer be useful.
Although the above large files are not included in the git repository, the local mirror of CTAN includes everything.
We will try to keep these services (currently they all run on one host) up and running as long as server space, connectivity, and bandwidth allow. If you find them useful, I happily accept donations via PayPal or Patreon to support the server, as well as my time and energy! —thanks, Norbert.