There is a saying when packing for the trail, if it doesnt have two uses then you probably shouldn't bring it. This post I found in backpacker magazine shows some funny and original ways to make dual uses out of some common items.
P.S. duct tape is always multipurpose. Never hit a trail without it in my opinion. It worked better for me than moleskin on blisters, cuts, etc., wrap around your trekking pole and boom your ready!
How and what do you use in two or more ways on the trail? I'd love to hear some creative ideas.