There's sort of an emerging Big 4 (plus 1) of FP

http://book.realworldhaskell.org/

http://programming-scala.labs.oreilly.com/

http://caml.inria.fr/pub/docs/oreilly-book/

http://www.freetechbooks.com/introduction-to-objective-caml-...

don't know of any freely available content books on Clojure or Erlang;