If you're into camping or survival practice, you could carry it in your pack for field sharpening. Guys and gals are all the time wondering what the best thing is to carry for a light field dressing of their favorite bush knife.
I've been wearing my brown stones out here lately (hehehe) and you got me to thinking when I have to replace them, maybe I can just break it in half and carry it in my pack. Maybe score it with a cold chisel where I want it to break.
You could replace that chipped one with a diamond set, I'm thinking maybe I'll do that.
EDIT: You can also rub two stones together, called lapping I think, to get the chip out...depending on how big it is of course. You wouldn;t necessarily have to use the other Sharpmaker stone, you could use an old carborundem bench stone, or 220 or 320 grit wet/dry on a piece of plate glass.