@[2] I think there's 6 or 7 leading families of functional lang's right now:

- you mention Haskell, Erlang , Clojure,

- plus scala, F#, ML family(ocaml), scheme family, common lisp family

- lots of complaints on tooling: clojure's emacs and vim plugins engender a lot of questions on IRC and the google gropu, same for scala's eclipse, netBeans and intellij plugins (many folk say, or said netBeans caused the least anguish for both languages, or emacs /ELPA, swank-clojure)

- books: Erlang, scala and haskell have excellent, up-to-date books, clojure they have several in preparation (the Fogus/Houser Manning EAP beta book looks really promising).

- open source/freely available content:

http://www.realworldhaskell.org/blog/

http://www.freetechbooks.com/functional-programming-f34.html

http://programmingscala.com/

http://books.couchdb.org/