So it's over. You'll miss that large fake palm in the corner of the lobby. You know the one, the one the new guy always got in their office until they wised up and put it back in the lobby? You'll miss the new guy too, and especially the long-timers.
Before you leave your job (assuming there's a transition period), do everything you can to connect with each person with whom you have a connection. It doesn't matter how random - maybe it's the guy you always parked next to, maybe your buddy who always ate Indian food with you, or the cute receptionist - but especially your co-workers, your subordinates and your boss. Let them know you'll miss them, be sure to get their phone number and email address, add them to your LinkedIn contacts right away.
Then, stay in touch! People that like and respect you want to have lunch or coffee with you. They want to know how your kids are and whether you've broken par yet. If you decide to go a different direction with your career, let them know. They might have a sister/cousin/neighbor/former co-worker in that industry. Get a new resume? Email it to everyone who likes you and/or whom you respect. Say something cute if it suits you, like, “Here’s my shiny new resume, in case you forgot how wonderful I am.” Whatever - just get it out there so people don’t have to remember all your skills and talents when they’re chatting up their Uncle Hal. They’ll remember you’re an analyst and if Hal is interested, they can forward your resume to him.
Then, get out of the house! Go to industry meetings, attend training seminars, and go to job fairs. Let people who may know someone who needs you get to know you enough to where you become a three-dimensional human being, not just a piece of paper (resume) applying for a job. Work at really getting to know a couple people at each place you go to on a more than just professional basis. People remember people they care about, or those that inspire, amuse or teach them. In addition, attending these events cements the idea that you're really committed to the industry, even if it's a brand new one for you. You'll learn something, have a cookie and be able to put the industry membership or new skill on your resume.
Remember that in every interaction, you're demonstrating how you'll be as a co-worker, boss or subordinate. Will you be natural, insightful and fun? That's whom I'd want to work with! I went to a recruiting industry meeting a couple of weeks ago and folks from Getty were there speaking. They shared a statistic that I've known to be true from my corporate recruiting days - 60% of the folks they hired last year for open positions were referred by someone at Getty or someone who knew someone at Getty. It's who you know. Does that sound bad? It shouldn't. Consider that I trust our mutual contact not to steer you my way if you're obnoxious, careless or otherwise unsuitable. Right there you're more "valuable" than the pieces of paper on my desk. They could be complete whack jobs, but you're golden if someone refers you.
So dry your tears and get out there!