Just got my first 4x4 ('11 700 Grizz) and I'm entirely unfamiliar with anything aftermarket. Does anyone make a second passenger seat for the '11 700 Grizz like I've seen on some of the Polaris 2 ups?

 

On the 2-up ATVs the whole ATV is set up for 2 people from the frame up. It starts out with a longer frame and goes from there. There's no way to stretch a standard frame into a 2-up configuration without a lot of custom work. If you want a 2-up machine buy one. It's safer than carrying a passenger on a one person machine.