Quack quack quick tips
The real key to duct-taping is to use the tape not sparingly at all. In addition to being totally inadequate for duct work, most duct tape doesn't stick very well to may surfaces, such as cardboard boxes. I know this because I was using some today (29/08/2001) to patch up the boxes I'm overstuffing with books and clothes. Judicious application of the silver wonder, down the seam of the opening as well as two or more parallel "suspenders" is the way to go with cardboard boxes.
Of course, there are some surfaces very well-suited to duct taping. Too well as I have learned. To make a long story short, don't use duct tape to hang speaker wire on white-painted walls. Especially those white walls with old, flaking paint that comes off when you try to get rid of the grey goo left behind by over-enthusiastic duct tape.
Trust me on this.