I learned long ago they are simply a cash cow you don't get to milk, for the most part. However, I tend to look at the technology and the price.
Last year I bought 2 36' LCDHDTV's for my daughters. I also got a three year warranty (bought two above the normal year)for both of them.
Sure enough, just a week after the original year ran out, one of the sets went on the fritz. They came and got it, fixed it, returned it. It would have cost about 1/2 of the original cost to fix it. This more than recoups the cost of BOTH warranties.
I consider this a fairly new technology, so I got it. Have it on my own LCD as well.
Phones, cameras, PDA's, etc. Not so much. But I would for a smart phone or blackberry or iPhone. Too much at stake not to have some insurance.