One way of dealing with a cluttered Source Editor is to unclutter
it. Another way is to keep the clutter but navigate through it more efficiently. (Kind of like not
cleaning your room, but working out how to make the mess work to your advantage.) Not sure if the whole NetBeans world knows about this, but if you click the Tab key while holding down the Ctrl key in the Source Editor, NetBeans gives you a little list containing all the open documents:
You can navigate through this list by holding down the Ctrl key while clicking the Tab key through the list. When you release the Ctrl key, the last document selected in the list opens in the Source Editor. Reading through this cool article about Mac OS X, Mac users seem to need to use the mouse wheel to get the same functionality.