The one exception was when I bought a Dell desktop almost 2 years ago - Dell offered me a deal with 0% interest for one year. I took 11 months to pay it off.
If they're dumb enough to offer me 0% interest, while still being the best price, I'll take it. Last laptop I bought I had the money in the bank, then when checking out they offered...
Gary, I have to agree with Hank. Worst case, would it have killed you to do without for a month? Also - keep a really close eye on special offers like the 0% interest schemes - most have HUGE penalties if you don't pay on time. It's one of the reasons I'll pay the laptop off a month and a half early - just to be safe.
My favorite is the local rent to own places. They offer stuff by weekly or monthly payments. A bigscreen TV NOW from one of them will end up costing you the payments for two years(per ad, they probably have different schemes available). Three months of payments will get you the same size big screen(and resolution) from Walmart, paying cash.
One of the reasons I ALWAYS discuss financial matters with my airmen. Nothing official, but I do my best to keep them away from pay day loan places*, rent to own joints, etc...
Stuff like 'Hold of on the TV for a couple months. Use the dayroom's until you have the cash to pay for it.'. 'You can usually get a really good deal for a car in the local lemon lot, you DON'T need a brand new Ford Explorer'. I'll also admit that I push the TSP a bit, but also encourage a traditional savings account 'for emergencies and unexpected opportunities/desires'.
*Especially before the military interest cap, but they've figured out some ways around even that...