You always need a pen. I don’t like not having a pen. I really hate it when I let someone borrow my pen, and they keep it!
How many times have you needed a screwdriver, but didn’t have one? Or needed a flathead but only had a Philips? I had to MacGyver a screwdriver a month or so ago http://bit.ly/dIDvP
532nm Pocket Laser
Umm….. Why not?