I took out 3 0% credit cards just before I went to the USA to do my PPL, banged £5600 on them in 6 weeks , then spent the next 6 months paying them off as I had planned , basically I had a free loan for 6 months, I still have them but no way will they get used now the 0% period is up, just there for a dire emergency now

as garath says, just exercise self control, only spend what you plan to and dont sit on ebay browsing through with them