A lot of people seem to believe that registrars monitor the availability queries at their sites and, for those queries that don't result in a sale, register the name for themselves. Here's a recent thread on just this subject. Every registrar employee to whom I've spoken about this denies it happens and says that with tens of thousands of availability queries every day and tens of thousands of registrations every day, the issue of someone querying for availability, walking away, and then having someone else register the same domain name days later is bound to happen....frequently. Perhaps someone can post a comment below or link to an article that could explain the registration process and why domain name "sniffing" doesn't occur.