I have always been a proponent of using 0% balance transfers as an excellent method of debt management. It has worked out very well for me. It never hurt my credit enough to have an effect–I was still able to get a great mortgage rate and used car loan rate. I successfully transfered a credit card balance to a 0% credit card several times and never paid a transaction fee. Over several years I paid off that debt without paying a penny of interest.
But Blueprint has provided some great insight in 2007 for methods to make money off of credit card company 0% balance transfer teaser deals. If you have the time, the balance room on a card and do not mind an small hit on your credit score these methods can provide an extra income stream.
FreeMoneyFinance has some thoughts on the 0% credit cards.