Just thought I'd post a little reminder about Wombat Game Tools, which is currently at v0.5 Beta. In addition to countless other little functions, it can view the planet pictures, screenshots and bonus level tiles (!) from JJ1. I haven't seen any strange mysteries in the bonus level tiles (nothing even reused from the normal levels!) but it's interesting to look at.
(You have to actually have JJ1 to view stuff, of course.)