I think it depends on the venue. I've had players drum their fingers on the table in OTB chess when that obviously wouldn't be an issue in Internet chess. Walking away from the board may be bad form in live chess on the Internet but is no problem for me in OTB chess.
The best answer I can think of is anything that would annoy you is something you shouldn't do to your opponent (using the general "you" here to refer to anyone, not you in particular:)
.