Gravitytank (one word) has a very thorough, 3-step interview process. They begin with a initial vetting via video call with a couple of team members on the discipline team you're interviewing for. Second round is a presentation to a panel of the whole (or most of) the team in your discipline. Third round is a full day of exercises with a mulch-disciplinary team. I didn't go through the last round, but did freelance there for some time.