Things you should buy warranties on from CC or Best Buy (Best Buy's are cheaper btw, though CC is generally better at customer service in my experience):
Game Consoles, portable mp3 players (especially IPods and expensive hard drive based units), cordless phones (depending on price) - covers everything in the box (controllers, head phones, whatever) against wear and tear and are "performance" guarantees. They don't repair these, they give you your money back in the form of a gift card; thereby you get the same price you paid for the PS2 2 years ago, to put it towards the PS3 or whatever. They truly don't care about these items so they're not going to fight you on them.
Large TV's ($800 or more I'd say) - In home service. If you're past the warranty you're screwed; the cost of one repair will be more then the price of the warranty.
Digital camcorders - Against, expensive as hell to fix. Annual cleanings, sometimes battery coverage.
Speaker systems or HTIB systems - Blow the speakers out, do whatever. You get new set.
Laptops.
That's what I say at least.