"How long will it run for?
21 days, unless you remove it sooner. Job seekers are generally reluctant to apply for older jobs than that because they may already have been filled.
What if I don't find anyone I like?
Thanks to The Fog Creek Promise, there's no risk at all. Just ask us within 90 days and we'll refund your money."
What's the incentive to not request a refund on day 22? (Besides being a tremendous douche.)
See point 7.
P.S., Joel, apparently you hired one of my friends as a summer intern. This guy is smart, earnest, and great to be around. What a good catch. I'm gonna try to finagle a Fog Creek visit through him ;)