Hollow Earth Expedition - or HEX for short - is an absolutely cracking RPG if you feel like punching Nazis in the face and feeding them to dinosaurs while defending your buddies with death rays at the center of the Earth.
The Ubiquity game system is a simple and clever binary dice system (evens=yes, odds=no, did you get enough yeses to succeed?) that runs very smoothly, and the core setting is supported with several beautiful sourcebooks — Secrets of the Surface World, Mysteries of the Hollow Earth, and the soon-to-be-released Revelations of Mars (c'mon dammit, publish it!?!) as well as some free adventures.
You can tell I like it, enough to go all out and design a Character Passport booklet. You can download it here.
The 10 page PDF is impaginated and will fit each spread on both A4 and US Letter sized paper, but will need a decent scalpel, metal edged ruler, stapler and quality printer to create. I found that printing it scaled down to 80% of the original size worked best.
So yeah, go try HEX.
Your fists will thank you for it.