git-branches-by-commit-date.sh

# Credit http://stackoverflow.com/a/2514279
for branch in `git branch -r | grep -v HEAD`;do echo -e `git show --format="%ci %cr %cn" $branch | head -n 1` \\t$branch; done | sort -r

output.txt

# Example output (resulting from running command on the Rails repo — https://github.com/rails/rails)

2012-02-12 03:20:24 -0800 9 hours ago 	origin/master
2012-02-10 10:34:35 -0800 2 days ago 	origin/3-2-stable
2012-01-31 09:56:12 -0800 12 days ago 	origin/3-1-stable
2012-01-24 11:18:06 -0800 3 weeks ago 	origin/3-0-stable
2011-12-31 05:09:14 -0800 6 weeks ago 	origin/2-3-stable
2011-11-25 09:49:54 +0000 3 months ago 	origin/serializers
2011-06-16 12:08:26 -0700 8 months ago 	origin/compressor
2011-05-24 16:03:41 -0700 9 months ago 	origin/sass-cleanup
2011-01-17 14:14:24 +1300 1 year, 1 month ago 	origin/2-1-stable
2011-01-17 14:13:56 +1300 1 year, 1 month ago 	origin/2-2-stable
2010-08-17 17:11:17 -0700 1 year, 6 months ago 	origin/deps_refactor
2010-05-16 22:23:44 +0200 1 year, 9 months ago 	origin/encoding
2009-09-10 17:41:18 -0700 2 years, 5 months ago 	origin/2-0-stable
2008-02-19 02:09:55 +0000 4 years ago 	origin/1-2-stable