I don't write reviews. Mostly because one needs to be thorough, unbiased, and have the gonads to tell it like it is, and I have a hard time with those things. (See Bryce's page for real reviews of modules.)
Nonetheless, I would not be a true brother-in-games if I did not tell you to get your virtual butt over to Al Krombach's blog and check out Warriors of the Red Planet. And by "check out" I mean buy a copy immediately. His blog is here. You can buy this 24-karat chunk of SwordnPlanet awesomeness for $3.93 here. (Yes, only 3 freaking dollars and 93 tiny cents--are you kidding me!!???)
This book is a complete RPG based on The Original, but rewritten to perfectly sync with the SwordnPlanet genre. (You can be a Weird Scientist PC if you want)
I've never really been much of a Burroughs fan, but I love love love some CL Moore and especially Leigh Brackett. If you're at all into that stuff, or even just want your fantasy campaign to look more like the airbrushed piece on the side of a 70's van, then this book is going to melt your brain and rebuild it with ancient alien technology so that it works way better.