Solutions to your problem:

1. You should get git. This is the best one.

2. They support Subversion. svn checkout http://svn.github.com/mrduncan/marker

3. They have a Mercurial plugin that makes hg able to interact with git repos. http://hg-git.github.com/

There is a "Download" button on the upper right corner on github site. It will download a zip/tar.gz file with the snapshot.

Enjoy: http://mrduncan.github.com/marker/