Lately I have been using Java/Scala + Play2 + MySQL and MongoDB/CouchDB. For some of my contract work I use the full JavaEE stack (including JSF, JSP, etc).

I have also used Python and Clojure quite a bit recently, and plenty of other frameworks and languages in the past.

Agree on the picking up of new techs being fun, probably why I have used so many different techs over the past few years.