[W-_-D]

I was really impressed with one of the interview rounds I was given at Microsoft - I was shown a mock code review and asked to comment on bugs (ranging from easy to spot like null reference exceptions, to harder like race conditions and edge cases) and code quality.

It felt like good fair test of someone's day to day ability, isn't really something you can grind for, and presumably also gives quite a good quantitative measure of a candidate if you assign a weight to each bug/quality suggestion.