Personally, I'm put off by the Leading Caps Style of Writing Unless it's a Headline, but that doesn't mean it performs worse than the alternative.
It could be cool, especially if you make a landing page specifically for the campaign. You link the Arc tutorial at the top of tryarc.org, but if you had a page that was tailored at Arc newbies, that would be a much better user experience. For example, have a special REPL that prompted the user to type something, and then recognized when they did it: "To add 1 and 7, type (+ 1 7). Now you try:"
Thanks for the feedback. The caps style is actually my present split test. I have caps and non-caps variations running for each of my 6 ads right now and will see in a few weeks how their performance compares.
I think a tailored landing page is a great idea. I worry about it not being clear enough how to get started for the people who click through.
Fair enough on the caps issue. I can't argue with "if it works better...", even if I don't like it personally.
Who do you want to target with this campaign? People learning programming for the first time, people learning a Lisp for the first time, or Lispers new to Clojure (and Arc)? You'll require very different instruction pages for each group. I'd be happy to help you write something, if you're interested. I'm sure many of us here would be.
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: