I honestly don't think 37Signals is changing the world in a big way. You're not inventing the transistor, you're making one of many online to-do lists and chats. I'm not saying the products aren't nice, they are. But they aren't gamechanging in any way.
It didn't change the whole world just a little bit (which is what most people mean by "change the world"); it changed one tiny segment of the world—webapp programming—a lot. I think that's even more laudable.
You're great at marketing though.