All she does is talk. Plus, she only blurts out obvious stuff.
"Link! I think Princess Zelda was just kidnapped!"
"Link! Don't look now, but I think you're wearing a green tunic!"
"Link! I'm the most annoying thing on the planet!"
Am I Right? (btw, for those of you who havent figured it out, Navi is the blue fairy from the Legend of Zelda who is always following link around)