All the time. It's default on eBay. I can pay with my credit card, without having to give my card details to anyone but PayPal. Also, I can pay from my bank account directly. I also buy things from people on different forums, and using PayPal gives me a sense of trust. I can use F&F if I know the seller and save the fees. Chase runs cash back promotions on PayPal from time to time as well.

At work we even run PayFlow for credit card processing, which is a PayPal company.