If you’re using Mozilla 1.0, you’ll notice that every window has a blue blob in the upper left corner. (Is that supposed to be a gecko?) It’s much nicer to have real icons that vary per component. You can fix this: go get the Grayrest/Giovanni icon set. You’ll be glad you did.
I was surprised what a big difference this made. It makes Mozilla feel more polished and really helps when you have multiple components such as the browser, JavaScript console, DOM inspector, and IRC chat all open at the same time.