Use the following command to find out how many commits there have been in a git repository. Not really useful in itself, but an interesting figure to see how active a project has been over it's lifetime.
git log --oneline --all | wc -l
The following git log flags are in use here:
--oneline - Removes some of the information from the log entries and displays each on a single line.
--all - Shows all commits across all branches.