I'd love to get some collaboration from the community here.
I agree 100% about different group requiring different landing pages. Both of the ones you mentioned are good targets, I think. I'll do more keyword research to help dissect the audiences.
The beginning programmers' page is easiest, because pg's tutorial already targets them:
"This is a brief tutorial on Arc. It's intended for readers with
little programming experience and no Lisp experience. It is thus
also an introduction to Lisp."
All we have to do is put the tutorial in an iFrame next to the REPL, as thaddeus suggested.  I can take care of this one. (Eventually it would be cool to have an interactive tutorial though, as you suggested.)
Can I get your input on a page that targets a Lisper who's new to Arc? They can be coming from the Lisp dialect of your choice.
I noticed within your feedback forum there were suggestions for REPL window size changes (for both bigger and smaller) and I got to thinking that when I wrote PetroEnergyNews (http://petroenergynews.ca/map ... which has a similar bounding box look to it) I did a bunch of experimenting with different systems, different monitors and different screen resolutions before coming up with the following optimal combinations: