What I love about Scala is that all (most, if not all) libraries built in Java can also be used. This includes those awesome apache libraries.

For Scala written libraries, here's a link to Github page: https://github.com/trending?l=scala

Whenever possible I avoid using Java libraries in Scala. Scala and Java have very different programming styles, which are codified in the APIs for libraries. You lose the benefit of Scala style when you are forced to program against a Java library.

For clojure, these are good: http://www.clojuresphere.com/, http://www.clojure-toolbox.com/, http://clojure-doc.org/

this is a pretty good blog, but it's best to ask on mailing list or IRC if googling cant find something

http://notes.implicit.ly/