Ok, so it's not the most exciting piece of gear in my bag, but my recent travels have sold me on the importance of having a monopod handy at all times. I'm a month and a half into a pretty severe case of tennis elbow (or "telephoto elbow", as I prefer to call it). Here's a review I wrote last summer about the Mountainsmith Trekker Fx Monopod and Trekking Pole. I really had no idea at the time how much I would end up using it. Stop taking your elbows for granted!
A combination monopod and trekking pole is a darned good idea and it is a tool that I've frequently wished for while hiking with my camera gear. The Mountainsmith Trekker Fx may not be the only one of it's kind, but it is the first one that I came across and it was a totally validating moment for me when I saw someone actually making a product that I had invented (if only in my own imagination). Carrying both a hiking pole and a monopod has always seemed redundant to me, to the point where I have actually considered installing a tripod screw into the head of my walking stick, but then…that would hurt my hand. Mountainsmith has thought of that, as well as a lot of other things that I never would have, so I guess that's why I leave product design up to others.