If you've worked with Web apps using Ruby, you might know of Rack, an interface that sits between Ruby applications and HTTP-speaking Web servers. All of the major Ruby frameworks and server setups use it now, including Rails. Middleware (in Rack) is code that manipulates data going back and forth between your Ruby apps and the HTTP server. You can use middleware to intercept requests, change data in mid-flow, etc. Ryan Bates has a great screencast tutorial if you're new to the concept and want to build your own.

P.S. I know the term "middlewares" sounds borderline insane, but.. it works, you know what it means - yada, yada ;-)

In this post, we're going to highlight various Rack middlewares from CodeRack, an on-going competition to build the best Rack middleware. So without further ado: