A whirlwind tour of Sinatra's most interesting features.
Detailed documentation on all of Sinatra's built-in options and using
disable to configure them.
Guide to testing Sinatra apps. Includes information on integrating Sinatra's test helpers with test/unit, RSpec, Bacon, and test/spec.
How to add new functionality to Sinatra using the extension APIs.
Answers to those questions most frequently asked on the mailing list and
List of applications, libraries, websites and companies using Sinatra.
Detailed change log for each Sinatra release generated from the
Generated from Sinatra's source with RDoc. The Rack API docs should also be consulted.
The Sinatra Book (Work In Progress)
An in-depth look at building and deploying Sinatra applications.
Adam Wiggins and Blake Mizerany present Sinatra and RestClient at RubyConf 2008. The talk details Sinatra's underlying philosophy and reflects on using Sinatra to build real world applications.
Classy Web Development with Sinatra (Prag's Screencast Series)
Adam Keys and The Pragmatic Programmers have started a series of screencasts on Sinatra. The first two episodes cover creating a tiny web app and creating a REST service. $5 a pop.
Peter Cooper's compendium with links to tutorials, example applications, and presentations.
Christopher's blog is a treasure-trove of useful Sinatra related information.