If you're memorizing, you're doing it wrong (IMO, in general).

I think that if you are working on some moderately challenging and varied personal projects, that's probably also a great way to prepare.

I used to think so, but I've found that small amounts of memorization alongside actually working with topics is so much more effective that I have started doing it outside of interview crams - such as when I am trying to get to grips with a new library's API.