When I solo or when I trip with a group, bear cans are used. These are hefty surplus naval gunpowder cannisters that are painted woodland colors, hidden near the base of a tree, and cabled to the tree. I have a picture of one in use in the Inukshuk Photo Gallery   (You need to Login or Register. I usually look for a bigger tree  ;). Sorry if you are not an Inukshuk  :'(.

So far, so good. None have been found yet so the effectiveness of the cans and their tethers has not been tested. On one occasion a timid bear was seen near camp, but didn't bother the cans nor anything else.

-aj