Design patterns for dynamically typed languages.
In Another Take on Design Patterns, Rick DeNatale has posted a friendly discussion of The Design Patterns Smalltalk Companion (I'm a co-author). He points out that the book explains the patterns from the original Design Patterns book with the perspective of a dynamically typed language. The language used in the book is Smalltalk, but the principles also apply to other dynamically typed languages like Ruby. Thanks, Rick.
I'll also point out that the book talks about development of business applications (whereas the original book mostly talks about frameworks). So if you're looking to apply the original design patterns in business applications or using dynamically typed languages, The Smalltalk Companion may help.