MongoDB in Action (free PDF)
Manning have been kind enough to allow me to give away a free extract from Kyle Banker's new book MongoDB in Action. The PDF contains the section entitled "Building a Mini-Application", in which Kyle shows you how to build a small Ruby application (using MongoDB and Sinatra) to search Twitter and display the results in your browser.
Grab the PDF and give it a read. When I bought the book I was working on a new MongoDB project with a client, but only a few chapters were available at the time. Every time I dipped into it I learned something useful. What I learned changed the way we built the app, and you can't do much better than that.
It's very well written and I found it a pleasure to read.
If you like the extract you can get the full book from Manning's site: http://www.manning.com/banker/