Yes, in a few cases
I always buy extended warranties for laptop computers (I have owned Apple's PowerBooks and iBooks) which take a beating as part of their use. Since I keep computers for 3-4 years, it is peace of mind and I have occasionally needed to replace parts that failed after the 1-year warranty period expired. I decided to buy the extended warranty for my desktop Mac Pro last year because it included free on-site service (which I needed that week), and that's much better than lugging a 50-lb. computer into a retail store and waiting an hour for a tech to look at it. I also got an extended warranty for my Panasonic plasma HDTV, but that was a special promotion by the manufacturer which included a 5-year extended warranty with purchase.
I don't normally extend my warranties for solid-state electronic devices, figuring they'll fail within a few months or not for years. On the other hand, many credit card companies, such as American Express, double your manufacturer's warranty (up to a year extra) if you buy a new product and pay in full with their card, and I will use that benefit in my purchase decision if it's applicable. It comes down to how long you expect the product to last and how much use you expect to put it through. Most seldom-used products last a long time through sheer inactivity. Items which you use daily may fail much faster.