I've had an ongoing dilemma when sitting down to work on Peeramour. I could write the site in Rails in an afternoon, which is tempting. Thing is, I write Ruby/Rails code all day. I'm burnt out on it. Plus, I'd like to learn something new if I'm going to be programming in my off-hours.
Looking around the landscape of web application development, only one technology has really caught my eye: Liftweb, a framework built with the Scala language, which in turn runs on the JVM.