Ember.js with dependencies, 83K minified and gzipped, +18K if you're using ember-data.

Gemfile

source 'https://rubygems.org'

gem 'rake-pipeline', github: 'livingsocial/rake-pipeline'
gem 'rake-pipeline-web-filters', github: 'wycats/rake-pipeline-web-filters'
gem 'uglifier'

gistfile1.rb

# Assetfile
require 'rake-pipeline-web-filters'

output 'build'

input 'assets' do
  match "core/*.js" do
    concat "dependencies.js"
    uglify
    gzip
  end
  
  match "extra/*.js" do
    concat "extra.js"
    uglify
    gzip
  end
end

gistfile2.sh

$ ls assets/core

jquery-2.0.0.min.js
handlebars.runtime-1.0.0-rc.3.js
ember-1.0.0-rc.3.min.js    

$ ls assets/extra

ember-data-latest.min.js  

$ bundle exec rakep

$ ls -lah build

83K dependencies.min.js.gz
18K extra.min.js.gz