Active corners with modifier!

I met someone recently who was using active corners to launch Exposé. I thought it was really cool and efficient, until I tried it myself. I kept accidently setting it off. I did, however, discover an additional feature that made these active corners worthwhile: active corners with a modifier. The way it works is that you hold down a modifier (Command, Option, Shift, etc) while setting the active corner. In this case, the only way to activate the active corner is by holding down the modifier while hovering over that corner with the mouse.