Invaluable.
I find grizzly bears to be a little loud once captured. Slap a 6 inch peice of duct tape over their mouths and you get a good nights sleep.
If you don't capture any bears, then you can always sleep well at night knowing whatever happens to your gear – there's a way to fix it with Duct Tape.
I simply take a big old length and wrap it around my hiking poles. That way I know where it is when I need it.