There's a nice article over at eWeek entitled
10 Avoidable IT Interview Flubs. They are called IT interview flubs just because it's eWeek, but 9 out of 10 can be applied to pretty much any kind of job interview. All of these tips sum up what I think is the key to any job interview: be modest yet confident. Don't talk too much, but you
must convey that you're knowledgeable
and a pleasure to work with.
It's definitely a thin line to walk. Too many times I've seen a qualified candidate miss out on a job because of just one of these annoying flubs. So don't be too much of anything during a job interview, the most well rounded (and grounded) candidate will usually get the job.