Scalatra (we had to pick Sinatra on StackShare since Scalatra is has not yet been officially added) is the slickest (not to be confused with Slick for Scala) web/applet server framework we've had the pleasure of playing with in Scala.

For all intensive purposes, Scalatra is the Scala version of Sinatra (which for anyone who doesn't know is a Ruby web server DSL). Sinatra