I went for an interview last week and I tanked in epic fashion, I was so bad I even told them I was during the interview. Afterwards they called me back in and told me that my nerves were too bad and that they doubted they'd seen the best of me. The upshot, I didn't get the job, obviously, but they saw potential and asked if I'd apply for a different position.
So, you never know what else might crop up.