Monopods are lighter and far more portable than tripods. But they're also not as versatile?unless you add a little extra support.
Monopods, otherwise known as one-legged tripods, have been popular with sports and outdoor photographers for years. They give you that extra bit of stability to help keep your photos as sharp as a tack.
The problem with monopods is that they can't stand on their own. Often this isn't a problem, unless you want to capture really long exposures of 1/4 of a second or more. Those are the times that you yearn for your tripod. The fact of the matter is that many photographers don't like lugging tripods around. This is especially true on long hikes, when you're trying to keep your equipment weight to a minimum. Happily, there's a solid compromise that is stable, versatile, and, most importantly, not too heavy.
Bogen Imaging (http://www.bogenimaging.com) makes a nifty device called the Monopod Support (catalog #3422), a modified ball-head mount that attaches to the top of your monopod. What's unusual is that it has a bracket that folds down and enables your monopod to stand on its own, er, two feet, as illustrated in Figure 1-4.
This special support head has a standard tripod socket in its base, which enables it to screw snugly onto any standard monopod. Once attached, you can hike comfortably with the bracket folded against the monopod. But when you need extra stability, you can loosen the wing nuts, pull the bracket away from the monopod, set your rig on a stable surface, and tighten the wing nuts to secure your setup. Now, you can use your remote release or self-timer to trip the camera shutter without jarring it.
I've made exposures several minutes long with the Bogen support, and I wouldn't dream of having any other type of mount on my monopod.