I really like it. It's a great project, guys. I like the art/design of it. I get it right away. Just some thoughts:

1) If I am not mistaken, I think your jscrollpane code is acting very wonky on some cases. jscrollpane default-styled scrollbar is popping up randomly. Double check the test cases to make sure.

2) mixpanel api script is dynamically putting intself into the DOM (head) multiple times

3) .directions a { text-decoration:none; } (for the "Make your own" button)

4) it seems that on initial load, the url-group pane goes up on any mouse click (left/right) and then acts normally.

Hope that helps and good luck. I think it's a very neat idea.

(Also, just a personal preference, but "brought to you by [Bundlenut] or [bundlenut.com]" look a bit nicer than "[www.bundlenut.com]")

-Vuong