I've heard a lot about Groovy in the past and I always wanted to learn more about it. What I didn't want though is a book that spends a chapter on what object orientation, another on explaining if statements and while loops and an appendix where the entire API is reproduced in order to pad out the book. I really wanted to get right into the meat of the language and start doing things right away. That's why I turned to the Pragmatic Bookshelf and Groovy Recipes: Greasing the Wheels of Java.
For those of you who are not familiar with Groovy it is a dynamic language that runs on the Java Virtual Machine and it can access the full Java API.
In Groovy Recipes you get a quick introduction to Groovy. Then you are off and running learning the fine differences between XmlSlurper and XmlParsers as the XML support in Groovy is top notch. There are sections on Web Services and working with Grails (Groovy web framework). Plus the topic of metaprogramming is covered in detail.
All in all the recipes are easy to follow and useful spring boards for your own ideas. If you are looking to learn more about Groovy you won't be disappointed with Groovy Recipes.