I'm sure it's been stated to death, but security work in the US has stupid amounts of downtime. My last site I was at, for my shift, I was literally on the computer playing Bastion, Civ 5, and whatever else I wanted for 7 out of the 8 hours. That was at a specialty clinic in Philidalphia, PA. My current site, after moving, is still 6 hours of downtime, the last 2 being the busiest. They're a little more strict on the personal electronics, but if you don't get caught they don't care. This one's at a distribution warehouse.
It pays 10/hour for nearly no work and requires very little intelligence, as represented by some of the people I work with. I'm using the down time now to finish studying astronomy and chemistry.
It's easy to get hired, too. The only things they look for are participants who can express themselves, have no criminal background, and can pass a drug test.
I was friends with one of the account managers so he got me in without an interview. From there I just went to whatever site looked easiest.