Plugins by Coda Hale
Dynamic session exp
Serves up session cookies with expiration dates set relative to the current time.
Replaces Rails’ default countries list with the list of countries to which the United States Postal Service can send mail.
A simple plugin providing a clean interface for determining which environment Rails is currently running. (e.g., Rails.development?)
Simple HTTP Auth
A quick, clean way of adding HTTP authorization to your Rails application. No need for complicated backends, gigantic user models, or other unneeded complexity. Just you, a password prompt, and whether or not someone should be allowed in.
Dollars and Cents
Stores prices as integers in your database, but access them as floats.
XHTML Content Type
xhtml_content_type allows you to set the default MIME type for rendered .rhtml views to application/xhtml+xml if the client supports it, and only falling back to text/html for older clients.
Allows your Rails application to take advantage of the caching mechanisms built into HTTP 1.1 (i.e., 304 Not Modified return code).
Find your tests' blind spots easily with Mauricio Fernandez's rcov code coverage tool and this set of dynamic Rake tasks.