Had 45 minute phone interviews (20 minutes of behavioral questions, then 25 minutes for technical/case questions) before receiving an on-site invitation. Once there, I had four 45-minute interviews that pretty much followed the same format. Topics ranged from testing popular websites to specific product features to statistical tools. Received helpful feedback on things I could improve on, and usually heard within a day or two whether or not I would move on to the next round.

General theme - If you want to test a feature/tool, what kind of datasets/inputs would you run through the system, and what would you expect to see?