Forgive a possibly newbish question; I have just discovered drracket, and am loving it!
One thing I am missing from emacs a lot is rainbow-delimiters-mode.
Is there a way to simulate this in drracket?
This would make the language a whole lot more accessible to us neophytes!
Somewhat off-topic, but maybe useful: @greghendershott is the author of the awesome Racket Mode in Emacs. You can absolutely use rainbow delimiters with Racket Mode, I do this every day 
I do sometimes use DrRacket, in particular for teaching, but I don't know enough to be able to answer your actual question.
There isn't rainbow delimiters exactly, but there is a similar, slightly more subtle thing, that you can find in the preferences dialog. Go to Colors, then Background, and then choose different options of the "Parenthesis Color Scheme" menu. Some of them are multi-colored, based on the nesting depth.
Thanks - yes I have used rainbow delimiters with Racket Mode in emacs and this is indeed fantastic… I too use emacs every day, but for other languages… but I am pondering if it's possible to get this user experience in drracket…
Why?
Well, in drracket I have to "keep off the grass" and keep on the racket path; in emacs there are too many interesting thickets to distract me…
In other words the fact that DrRacket is focused purely on racket has great appeal to me. I know that Emacs is The True Way - but for folks who are interested in just the language and not the editor, as I am at the moment, DrRacket is great… except for all those perplexing, same coloured parenthesis!
Ah! thanks - "shades of blue" is definitely a step forward!