An enormous body of literature has been published on design patterns in the last decade and a half. The literature on Ruby is certainly growing day by day. This appendix points out some of the resources that will be of particular help to the programmer who is interested in both Ruby and design patterns.
Gamma, E., Helm, R., Johnson, R., and Vlissides, J. Design Patterns: Elements of Reusable Object-Oriented Software. Reading, MA: Addison-Wesley, 1995.
I am a big fan of reading the original literature, and if you are interested in design patterns, there is no better source than Design Patterns.
Another, less obvious choice, but one that is well worth the time is
Alpert, S., Brown, K., and ...