Data Structures and Algorithms with OO Design Patterns in Ruby
Data Structures and Algorithms with Object-Oriented Design Patterns in Ruby is an online book (free to read!) by Dr. Bruno R. Preiss, an incredibly well qualified engineer and computer scientist. It covers all of the various data structures and algorithms that beginning Computer Science students have to learn, but from a Ruby perspective and using object oriented design patterns.
The book itself is now a few years old, but I've only just come across it and it still seems relevant although, rather sadly, the on-page code is in graphics only (a ZIP file containing the source is available) and feels like a line-by-line conversion from C++ rather than true Ruby code. Still, if computer science, data structures, and algorithms elude you to any degree, and you want to learn about them while following Ruby code, it's a good place to start. There are also versions for C++, Java, C# and Python available from Bruno's homepage.