most common i've used across projects lately (by no means all just most common)
- RESTful Authentication
(http://github.com/technoweenie/restful-authentication/tree/master)
- Acts As State Machine
(http://github.com/rubyist/aasm/tree/master)
- Mislav's will_paginate
(http://github.com/mislav/will_paginate)
- HAML & SASS
(http://github.com/nex3/haml)
- RSpec
(http://github.com/dchelimsky/rspec)
- RSpec-Rails
(http://github.com/dchelimsky/rspec-rails)
