An absolute must have for me. Along with regular drumsticks I keep mallets of several different types, brushes, & Hot Rods. Only sad thing is that they never last that long. Doesn't matter. I'll always keep a couple sets in my stick bags.
There are so much more texture in playing drums of any kind when you get creative with it. Be it the option named above or- one of my favorites- Bowing the head of a drum. The options hardly stop there so go get weird on some drums if you feel like it. So much fun.