I'd say shamelessly copied from the much better article from here:

http://git-scm.com/book/en/Git-Basics-Viewing-the-Commit-His...

I once needed a ChangeLog file, so I wrote this:

# create ChangeLog file out of git history

alias g.changelog="git --no-pager log --format=\"%ai %aN %n%n%x09* %s%d%n\" | sed \"s/\\ \/*/g\" > ChangeLog"

g.ch<TAB> completes it for me in zsh.