Duct tape can usually be ripped pretty easily. If not, just clip it with the nail clippers and rip it. I have never had a problem ripping duct tape. They also have duct tape strips. I got mine at WalMart.
You can use duct tape for lots of things. Some I can think of right now are:
To mark your luggage so it's easier to find at debarkation.
If cabinet doors or drawers tend to "bang", a piece of duct tape will stop that!
If part of a hem comes out-duct tape it!
"A truly happy person is one who can enjoy the scenery on a detour."