Do you keep in touch with candidates who you didn't bring on board? I didn't think so.
You need to! You may have candidates who came in 2nd place to the person who was offered the job. Those are prime candidates for future vacancies.
Do not lose their attention. Nurture those relationships or else they will go find something else, making your work harder when you have to go out and find another great person to fill a job.
Remember: it's not all about you as the employer. Wow the candidate by staying engaged and they'll consider working at your company in the future.
P.S. - Ignore the random piece of hair that is posing as a headset microphone.