Code review, if possible. Students of computer science write a lot of code for assignments and projects; I want to see some of it. Obviously, it makes sense to judge the students more leniently than I would judge finished professionals. Grades in relevant courses are also a useful signal.
If a student insists that he has no code suitable for review, fall back to coding problems, since coding under unrealistic conditions is better than no coding at all. But in such cases I have to wonder what the heck the student has been submitting for assignments and projects, so that's definitely a minus.
