Paying for github private hosting seems the quickest way. The network viewer is totally proprietary.
There are patches over on repo.or.cz that add a similar interface as gitk to the vanilla gitweb front end. It is, or at least was when I tried it, a complete pain to set up but is doable for your own projects.
The output is really like gitk, like it or loathe it, so if you are used to that it is familiar at least. Here is the graphical log of git itself.
