One thing I like about Go is the Go Playground and the Tour of Go. Is there something similar for Racket? Obviously, I can use the REPL or DrRacket and that's fine. But what I would love is a site where I can play with existing code that teaches me various aspects of the language. Nothing beats breaking things to teach how things work.
Side note: brand new to Racket and so far I really like it. Plus, I find the documentation to be outstanding — on a par with the FreeBSD handbook.