Michal Chaniewski also has some interview tips. One thing that strikes me about the lists of interview tips I've read recently is that if you haven't spent a substantial amount of time preparing for an interview then you're doing yourself a disservice. Or you don't really want the job, in which case why not think about what you really want to do and which jobs you should be aiming for.
A work colleague made an observation recently that it is much easier to succeed at an interview if you are currently working on something exciting. If you're stuck in a dead-end job, say bug-fixing customer problems all the time and hating it, you'll find it more difficult to come across well at the interview. Of course the problem here is that you are much less likely to be looking for another job if the current one is exciting. One way out of this dilemma is to have a personal programming project or contribute to an open source project; anything to give you a sense of pride and ownership and so boost your morale. It will also makes you stand out from most or all of the other people applying for the same job.