Perform Yahoo searches in 2 lines of code
Step 1: Get the Yahoo-Ruby API. It's only a small Ruby file. Its only dependencies are net/http and REXML that come with Ruby anyway.

Step 1: Get the Yahoo-Ruby API. It's only a small Ruby file. Its only dependencies are net/http and REXML that come with Ruby anyway.
An oldie but a goldie.. Kent Siblev had an issue with his Rails application ballooning to 150 megabytes of memory usage per process. He couldn't figure out where the problem was, so he wrote a small plugin called MemoryLogging to check memory usage on each request (Linux only, I'm afraid). He found his problem within minutes and explains what was going on.
This is a "short" Ruby on Rails reference. It's goal is to give you an overview over the most used functions / methods / classes. It's not a tutorial, but as a handy guide when you already know your way around.
Devin Steffler shows you how to load over 100000 countries, states, and towns into your Rails app's database, from how to get the data to the code to transform the data into database entries.
Stuart Halloway and Justin Gehtland of Relevance LLC have put together an online presentation called AJAX on Rails. It looks at AJAX, its relation to Rails, how Prototype works, and provides lots of great code examples. If you want to brush up on your whole AJAX and Rails knowledge, it's worth looking at. A PDF version is also available.
Basic Ruby

Sebastian Delmont has put together a great PDF presentation covering most of the different ways to find things with ActiveRecord in Rails. Excellent.
Tar2RubyScript is a tool that packages up your entire Rails application into a single tar file with a special loader so that users can get up and running with one click.

In this photo, a Ruby script has found the license plate and marked it with a red box (source below).

Another new article in Bruce's series shows you how to get DOM-friendly IDs from ActiveRecord. This is a solution nearly all Rails developers have implemented at some time or another:
NArray is an Numerical N-dimensional Array class. Supported element types are 1/2/4-byte Integer, single/double-precision Real/Complex, and Ruby Object. This extension library incorporates fast calculation and easy manipulation of large numerical arrays into the Ruby language.