GitHub provides the best web-based git repository browser, as well as various other useful features. The only other reasonable alternative for a large open-source project, aside from self-hosting, is bitbucket.
You like cvsweb? It's horrible. I'm here: http://cvsweb.openbsd.org/cgi-bin/cvsweb/CVSROOT/. Why does not clicking a file open the file?!?!? Every freaking file browser in existence opens the file when I click it. It's been designed in the 90s and it shows :(
Lot of replies here disagreeing that GitHub is "the best", and offering alternatives.
Allow me to suggest that GitHub is at minimum the most-visited web-based git repo, which means that if you want a lot of people to view and use your code, it's a good place to mirror.
https://hg.python.org/cpython/
Another interface I prefer is:
http://cvsweb.openbsd.org/cgi-bin/cvsweb/