Snakes should be a given, especially for RP purposes for Set worshippers. My brother in arms @Necro put out the call for them to be added as Pets a while ago now. Despite being VERY popular (see below), it still hasnt eventuated. I just dont get the resistance.
Sandbeasts and Demon Bats dont look to me like they would repond too well to being domesticated, at least not by humans. But as someone who is always looking to see more darkness and brutality injected in to the game, Im on board. 
Upvoted.