These days, if you go out to buy anything from a weed-whacker to a car, you are going to hear an extended warranty pitch. Cheese (salesmen lingo for service plans) makes everyone a lot of money. Back in the old days of Circuit City when the salesman were on commission, these service plans paid 15% commission (I used to be one) so if you sold $500 in cheese, then you walked away with 75 bucks in just warranty, let alone any accessories you sold with it. Digital Home Canada has a great write-up on how exactly they work and who they pay. They are recommending not to buy 'em, but we here at HDBeat are saying don't throw the idea right out the window by looking at the plan and seeing if it works with how you are using the product. For example, if you are buying a DLP that has a lamp life of 4000 - 5000 hours and the set is on for 12 hours a day (12 hours a day x 365 days = 4380 hours in a year), then it might make sense if the cost of the warranty is anywhere near the cost of a lamp. But if that DLP is only on for the occasional movie or sports game, then it probably doesn't make sense. All we are saying is understand how the TV technology works before you decline that salesman. Keep in mind you usually have a few weeks to come back and buy this service plan, so take some literature and read up about it.
What do you think about extended warranties? Did you buy one for your HDTV?
NOTE: There has been a lot of discussion in the comments about how some retailers do not cover the lamp, but Best Buy's and Circuit City's service plans does cover the bulb.