he just said slick....
only issue with slick is that you HAVE to sign it.
Slick isn't really an engine, it's more of a library.
Most of the people on this site don't use engines, although jME is pretty popular (although again I wouldn't necessarily call it an engine, despite it being named as one).
This isn't Java, but I've found the
Unity Engine to be very powerful and easy to use. Support for it is also incredible. You'll have to program in Javascript, C#, or Boo, but C# is very very close to Java and Javascript is obviously just a stripped down version in many ways. Unity will handle scene object placement, physics, code, etc. for you, so it's a pretty nice tool. Plus they made the indy version free now.