Useful Rails plugins ,Ruby gems and Ruby libraries

I have seen many websites which provides a bunch of Rails plugins ,Ruby gem and Ruby libraries in which many of them doesnot suit our requirement and most of them doesnot work due to lack of support . Here are some of the resources that i have aggregated from the experts who have worked on these resources. Hope this helps !

• Contacts is a universal interface to grab contact list information from various providers including Hotmail, Gmail and Yahoo.
• Mofo gem – A ruby microformat parser , Helps to import Profile data from networking sites which implements microformats using hResume,hCard . ex LinkedIn , Xing ,Twitter etc .
• Backup-fu - in conjuction with capistrano, we always backup before a deploy to Amazon S3, and set cron jobs that periodically backup the database and asset directories.
• Capistrano - For easy rails deployment on shared host like Bluehost ,Hostmonster etc.
• Paperclip plugin for simple file uploads in Rails .
• Will Paginate - Plugin for essential pagination in Rails Application .
• Formtastic is a Rails FormBuilder DSL (with some other goodies) to make it far easier to create beautiful, semantically rich, syntactically awesome, readily stylable and wonderfully accessible HTML forms in your Rails applications.
• RSpec – Behaviour Driven Development framework in Ruby
• Thinking Sphinx - Thinking Sphinx allows you to link up your models into Sphinx simply and painlessly -– because let’s face it, searching across multiple fields using SQL is a pain in the neck.
• Populator – Ruby gem which populates an Active Record database with mass insert.