For just browsing files and revisions git instaweb is the right solution.
In addition if you want to set-up an ad-hoc git server for sharing work (push/pull) with some colleagues (which hg serve also allows you to do), you can use:
git daemon --reuseaddr --base-path=. --export-all --verbose --enable=receive-pack
Your colleagues will use it with something like:
git clone git://<ip-address>/.git project
Addition 1:
If you want to be able to push to this server, you need to add the --enable=receive-pack option (Thanks to Dominik below).
Addition 2:
It just happened to me so I add it to the answer :-), if you are using a Redhat-based Linux distribution (RHEL, CentOS, etc.) and have an error "git: 'daemon' is not a git command.", then you need to install a seperate package for it:
sudo yum install git-daemon