I've been using the X-acto cutter in my pencil jar on my desk. Amazingly enough, it makes the best cut I've ever found. I think they're 8 bucks, blades are replaceable, and they work great for opening cigar boxes without wrecking the seals.
I only do this because I don't know where any of my cutters are. There's one in the car, but I'm not going out there to get it.
Behold la'innovaccionne!!!