Try Asimov. I remember reading some of his work on robots years ago and he was good with giving them...quirks. Like the robot that essentially 'twidled it's thumbs' (only, instead of thumbs, it moved around other robots that it controlled, or something like that). Idle behaviors seem unremarkable in a human, but in a robot...it can be something memorable.
Little, unique, weird things can breathe life into a regular character, so why not a robot too? Perhaps one robot enjoys decorating itself with magnets, much to the confusion of it's designers. Perhaps one has no concept of a personal bubble and stands way too close to people (or perhaps it does it on purpose, aware that it unnerves them). Maybe one likes to bend forks into unique shapes when it's feeling frustrated. It all depends on how far you want to go and what you're going for, and how 'human' or how foreign you want to make them.
