1) Chamber of Commerce Offices (membership at 2)
2) Executive Suite Office Complexes (they deal with temp and short term offices and this sometimes is
as a result of a move.)
3) Headhunters (Married to one, but solicit others, too.)
4) Networking with Realtor groups - CRS :)
Open to hear ideas from others and read their \posts. Good question!
Cartus and USAA relocation networks are great, and they don't only work with large national companies. Have your broker check into what it takes to get approved. I know they have primary and secondary brokers in most markets. Though I am part of a large company and part of the Cartus and USAA referral networks, I get more relocation business from leads I generate myself.
One of the things I have done that has been very useful is visiting local businesses and HR departments. Even if a company only has two people moving in in a year, I want them to think of me first. I put an area info package together to leave with them. Also, once they get to know me, they allow me to bring in listings. Some companies HR departments will even post the listings for me. Even if the company already has a relocation program, I talk with them. As you might know, one very large national real estate company recently scrapped their relocation program because it didn't work with their agent's commission structure (few agents were willing to pay a referal fee). This has left an opening in a lot of areas.
I also attend conferences whenever possible and take my CE and designation classes out of town. Not only do I get to meet realtor's from other markets, but I also try to choose areas where I might want to spend an extra day or so (class at the beach, anyone?) I always write a personal note to my classmates when I get home and make sure to stay in touch. I've ended up with new friends, new places to visit, and great contacts! I add contacts from conferences to my data base, noting who is part of my relocation network. Because second and vacation homes are a large part of my market, I also notify these contacts when I have a new home come on the market.
Don't forget all of the people you know in other areas. Old college buddies, your great aunt, ect. I use christmas cards and other holiday cards to stay in touch. I try to send something or call once a month, just to remind people that I am there.
Outgoing referals are great too. Just because you may not be part of a network doesn't mean you can't form your own on a smaller scale. Other agents you meet in person, in online classes, or here on Trulia are great. It's nice to get a referal check for making a couple of calls. They will definately think of you first if they or another agent they know comes across someone moving to your area. Your friend in New Jersey may be moving to Chicago and you are in Florida. You can still help by finding them an agent to sell their home through contacts you have made, and to find their new home the same way. That's two outgoing referals, your friend is happy and two agents (and their friends) will think of you whenever they think of Florida.
I know some of this may seem remedial, but I hope it helps.
BTW, feel free to contact me and I'll add you to my personal network. You never know when I may have someone who needs help in your area.