http://github.com/brianmario/yajl-ruby
The new JSON gem compatibility API is meant as a drop-in replacement for the JSON gem in your projects.
Simply replace "require 'json'" with "require 'yajl/json_gem'" and you're set!
yajl-ruby offers a more efficient, better RFC compliance and Unicode support over the JSON gem. I highly recommend anyone using the JSON gem to check it out.