Using Firefox has cracked open my mind to this open source ecosystem. You don't like something about the product, you create an extension that fixes it. And publish it for the rest of the world to use.
As Kim Polese said at Web 2.0 today, "The rules of open source: nobody owns it, everybody can use it, and anybody can improve it."
An entrepreneur recently told Technoflak that using open source was a big plus for a his company. If prospects express doubts about his company’s future, he can say that his product is open source and once they buy it they own the source code. This is a tremendous confidence builder for small companies.