* Great non-emacs Lisp IDE, powerful, cross-platform, and easy for newbies (but emacs works fine too)

* Tons of interesting language extensions -- any Scheme you have ever thought of -- implementations of laziness, static typing, logic programming, FRP

* Very good online documentation

* Great libraries for lots of things, combined with really easy online package management @ http://planet.racket-lang.org/

* Go look at all the cool things it does, don't they look fun? http://docs.racket-lang.org/