These are some of my (Ryan Bates) favorite gems to use for various tasks:
- JavaScript: jQuery with jquery-rails
 - Pagination: Kaminari
 - Testing: RSpec, Cucumber and Capybara
 - Factories: Factory Girl
 - Authentication: Nifty Generators and Omniauth
 - Authorization: CanCan
 - File Attachments: Carrierwave
 - HTML/XML Parsing: Nokogiri