One alias that I find really useful is,

summary = !git log $(git log -1 --merges --pretty=format:%H)..HEAD --oneline

This prints the log summaries on one line up to the last merge commit. If you are working on a feature/topic branch (and you collaborators do too), this will just print out the commits you have add for the feature. I often use this to go back and rebase fixups or suggestions from a code review.