In the spirit of one of my favorite blogs, Homages, Ripoffs, and Coincidences, I'll share two elements that struck me.
Arnold Poindexter, the tall awkward nerd, is the archetypal character that defines Napoleon Dynamite. You can seen the similarity in the images below, but seeing them on screen (speech patterns, humor, attire) is even more revealing.
Arnold Poindexter from Revenge of the Nerds:
The other iconic scene is the rock show the nerd do for the Greek Games at the end of the movie. From the moment the scene began I felt a strong sense of deja vu; as if Jack Black closely studied this scene as source material for School of Rock. It's not just the rock show finale, but many persona's of the cast seem to draw heavily from characters defined by Revenge of the Nerds.
Revenge of the Nerds:
School of Rock: