I'm a longtime member at fatwallet and have done my little share of applications and balance transfers for free (or almost free) short term money. Since I had to buy a car and <em>thought </em>we were going to purchase a home a while back, I stopped to allow my credit score adjust back to 700+.
Currently, my only outstanding balance is $10,000 that's earned me several hundred dollars in interest. It's a 0% APR Discover Card that doesn't expire until the balance is paid off or I default. At one point, I had a measly $30k floating around earning 5%. It's nothing compared to the $100k+ that some people pull from their credit cards. All I've really lost so far is some time reading the fine print and making sure I know the "Terms and Conditions" inside out.
Is it worth it? It depends on the person. I'm the type to keep a mental balance of all my savings, CDs, checking, investments, and credit cards. I know the due date of all my bills and cards. My friends may say I'm obsessed with money but I look at it as just a hobby. On the other hand, there are people (like my SO) who don't want anything to do with paying bills.