Next Up, I'll talk about preparation for the High Road to Hell.
Darwin's World is a third-party campaign setting for d20 Modern, WotC's venerable, out of print Modern line using the OGL. Fortunately, while the d20 Modern print books are long since out of print (though they can still be had second hand rather readily), the Modern SRD is still available for the asking, and a nice PDF of the MSRD rules can be had free from Darwin's World's publisher, RPG Objects. Darwin's World is simply the best d20 post-apocalyptic setting out there, with a broad range of support, and a very plausible, post-nuclear setting.
The High Road to Hell is another published adventure. My responsibilities here have mainly extended to building serviceable pregenerated characters, drawing up maps, and getting things ready to run. I've still got a few maps to do, but that should be finished by tomorrow afternoon. High Road to Hell is basically a wilderness adventure where the PCs are attempting to catch up to and rescue some kidnapping victims while racing the clock to do it.