Useful books and resources concerning Groovy/Grails

When I just started with Groovy/Grails I faced the problem of finding good books/blogs/resources. Therefore I want to share some useful links for the beginners:

1. I recommend Appress books concerning Groovy/Grails especially Beginning Groovy.
2. Grails reference is quiet laconic but useful in any time.
3. If You have any problems or need qualified support I recommend Nabble forums, there are a lot of posts concerning Groovy/Grails problems.
4. Blogs on www.blospot.com

This post will be updated frequently cause I will try to ind more useful resources.