Castles & Crusades 2010 Primer & Quick Start from Troll Lord Games. This was Troll Lord Games Free RPG for 2010. If you haven't tried C&C yet, this is an easy way to check it out. If you have played C&C, this is an easy way to show your friends (yes, I like C&C... hate the Crusader mag tho')
Battlestar Galactica RPG Quickstart Guide from Margaret Weis Productions. 32 page into to the Battlestar Galactica game based on the recent TV series of the same name. Sorry, my Cylons had the bouncing red eye.
Mutants & Masterminds Beginner's Guide from Green Ronin. Green Ronin always puts out top notch products. The new DC Heroes Games is going to be based on M&M. Take a peek and see if it might be something you'll like.
Hackmaster Basic Quick Start from Kenzer Co. This is the shortest quick start so far, just 6 pages. Still, that means it's quick to read so theres no excuse not to get it. You'll have to scroll down on the right hand side of the Kenzer Co web page that is linked to find the quick start PDF, but what is 6 seconds of work for 6 pages of gaming? Correct! A damn good ratio! heh
Geist: The Sin-Eaters Quickstart from White Wolf. The 2009 entry into WW's World of Darkness Setting using the Storyteller System. I haven't checked out the World of Darkness setting since Monte Cook did a D20 version, but this might need to be chacked out.