List remote Git branches and the last commit's author and author date for each branch. Sort by most recent commit's author date.

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="%ai %ar by %an" $branch | head -n 1` \\t$branch; done | sort -r

output.txt

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

2012-06-20 14:21:23 -0700 3 weeks ago by Aaron Patterson 	origin/master
2012-06-17 01:23:02 -0700 4 weeks ago by José Valim 	origin/3-2-stable
2012-06-15 20:36:09 +0200 4 weeks ago by Piotr Sarnacki 	origin/actionview-extraction
2012-06-14 10:55:30 -0700 4 weeks ago by Aaron Patterson 	origin/3-1-stable
2012-06-12 20:05:46 -0700 4 weeks ago by Aaron Patterson 	origin/3-0-stable
2012-05-29 10:40:14 +0200 6 weeks ago by Piotr Sarnacki 	origin/cat-gemfile-test
2012-05-27 14:01:44 +0200 7 weeks ago by Piotr Sarnacki 	origin/helpers-order-fixes
2012-05-27 01:47:37 +0200 7 weeks ago by Piotr Sarnacki 	origin/possible-railties-fix
2012-03-29 06:26:32 -0700 4 months ago by Xavier Noria 	origin/2-3-stable
2012-03-02 15:01:20 +0100 4 months ago by Sergey Nartimov + José Valim 	origin/opt_routes
2011-11-25 09:49:54 +0000 8 months ago by José Valim 	origin/serializers
2011-06-16 12:08:26 -0700 1 year, 1 month ago by wycats 	origin/compressor
2011-05-24 16:03:41 -0700 1 year, 2 months ago by wycats 	origin/sass-cleanup
2011-01-13 15:42:28 +1300 1 year, 6 months ago by Michael Koziarski 	origin/2-1-stable
2011-01-13 15:33:38 +1300 1 year, 6 months ago by Michael Koziarski 	origin/2-2-stable
2010-08-17 17:11:17 -0700 1 year, 11 months ago by Aaron Patterson 	origin/deps_refactor
2010-05-16 15:20:52 -0300 2 years, 2 months ago by Santiago Pastorino 	origin/encoding
2009-09-09 22:25:23 -0700 2 years, 10 months ago by Beau Harrington 	origin/2-0-stable
2008-02-19 02:09:55 +0000 4 years, 5 months ago by Jeremy Kemper 	origin/1-2-stable

I need an updated version with Author -> Branch Count list

I think this will get you pretty close:

for branch in `git branch -r | grep -v HEAD`;do echo -e `git show --format="%an" $branch | head -n 1`; done | sort | uniq -c | sort -rn