Dirty Labs and Dangerous Jungles is a set of pulp extensions for the free Wild West Skirmish Set, Black West. Both can be found on this page.
Thrilling Tales is a neat site with a neat, pulp-ish, smartly illustrated multiple branching story. It’s hard to describe, so give it a visit and play around.
EGBZine is an online archive of more than 10,000 pages of Edgar Rice Burroughs goodness — stories, articles, art and more. If you’re contemplating (as I am) a John Carter of Mars game, this is a good place to start.