There are students at my college that use unicycles to get around campus, which makes alot of sense. It's faster then walking, and the unicycle is small enought they can bring it into the classroom with them. No worries about getting them damaged or stolen at the bike racks, something I'm jelous of. And most have some way of attaching there unicycles to their backpacks as well so they don't have to carry them around in buildings. I'm not so sure about riding one for 5km or more though, I ride about 8 miles to school and couldn't imagine doing it on a unicycle. How fast can those things really get going on flat ground???
There is a small group that rides around Minneapolis, MN. I see them frequently on West River Road. I think it's a small club, usually riding together. They ride the big wheeled unicycles, like 26" mtb wheels I guess. They stay on the bike/running paths and I've never seen any problems.
Trying to find out if any bicycle loving members of this forum ever had the urge to subtract one wheel and take wild ride on a unicycle.
I rode a lot as a teen, haven't since then, but am always interested in a good deal on a used uni. Many of them are crap, though, and I'm not interested in buying junk. I may build one, when I get the time.