"For example, their maps or online doc or shopping search or payment systemed were no better than what others offered,"
Seriously? Because from my perspective they did an incredibly innovative user interface that made maps suddenly interactive instead of click-and-wait by quantum movements. It felt like I could access an installed mapping application from anywhere without actually committing huge resources to install it. As soon as I saw their interface, I never went back to mapquest except when websites would publish a mapquest link as their location. They also opened up the API, allowing others to use or layer the information (and I don't know how they made money with this API).
I don't know about their shopping or payment system improvements and I have not been as impressed with what I have seen, but if I were after the quick money I would focus primarily on this.