We include a fizzbuzz-style coding question in the job posting itself, and ask people to include an answer with their application. 90%+ don't bother (the ones who are just spamming resumes) and can be immediately ignored. Of the remainder, at least half can be cut pretty easily based on their submission. Usually the remainder make one of a set of minor mistakes, or if not, there are several ways to approach the problem, so either way there's something straightforward I can write back to ask. Usually manage to whittle the list down a bit further based on those conversations, and usually then I'll look at resumes.