At starwars.com is available a new soundboard: DROIDS
And there's one sound labeled as "Lobot"; it's a strange sound I've never heard in the movies... clues anyone?
Speaking of droids: Ady, did you check on Anthony Daniel's face beng visible in the scene that Chewbacca had screwed (sorry) 3PO's head backwards?
(Example captures here and here)