\TCav is right about the landscape shots, that you could boost your ISO, shutter speed and all if needed to help you get a good shot handheld. When I decided on getting my Manfrotto-Bogen monopod, I got mine specifically for low light since I do like to photograph some special items in museums that have dim light anyway. However, I also got an extension arm that attaches to the monopod that serves to help me brace it against my shoulder and it has an adjustable length locking mechanism. The monopod is really light although the 2 heads I can attach to it are actually heavier than the monopod (but both will stay rock-solid). The main use that will be more practical for a monopod will be those low-light museum or church situations. The only way I'd say having a monopod is practical outside for landscape photography would be IF you didn't have a tripod (or carrying a tripod is too heavy) and you'd want to be able to place the monopod at odd angles to the ground on a hiking excursion--but you'd have to have something to brace yourself against to steady the monopod for good measure.
what brought this question is, when i read reviews on monopods , for some reason it is alwaysassociated with sports photography, so i wondered ,if the monopodis only used when a big lens is being used or can it be used for landscape and low light with a standard zoom and would you benifit by using one
Pentax K20D / D-BG2
DA*16-50 : DA*50-135 : 360 FGZ
Tamrac velocity 8X / Domke F3X / lowepro stealth reporter 100AW