well, you can navigate through open windows using the arrow keys. I use apple+down arrow to open folders, docs. Or in column view (hit apple+3) you can simply use the arrows to go backwards and forwards through folders (with apple+down arrow to open a document)
To jump to an item in the window, hit the letter key corresponding to the first letter of the item you want. eg. in applications, to jump to quicktime, hit 'q'
I believe it's entirely possible to navigate through OS X with just the keyboard, and no mouse.