This could be mobile...
ThisCouldBeMobile.com is a way to demo what someone else's site would look like if they added a mobile-responsive CSS file.
Recently I've found a lot of sites which would be good to have on my phone, but they didn't invest in mobile-responsive CSS. If they're not on GitHub, it's difficult to write to them and say "hey, add this file to your website." So I made a website that demos what your CSS file does, with instructions about how to add it.
Setup
Prerequisites: git, MongoDB, NodeJS, a Heroku account
git clone https://github.com/mapmeld/this-could-be-mobile.git
cd this-could-be-mobile
mongod &
npm install
npm start
heroku create my-mobile-recommend
heroku addons:add mongolab:sandbox --app my-mobile-recommend
git push heroku master
CSS Viewer
CodeMirror powers a CSS viewer
License
Open source, MIT license