Autoresponder is a kind of marketing tool that can be used in any field or any kind of business.
No matter you do offline or online business ...
No matter what you sell, garden tools or land properties ...
Four ways a realtor can use Autoresponder in his business:
1. Send newsletter to your subscribers:
Give your web site address to your potential clients and ask them to sign-up for your newsletter to get up-to-date information on property sales.
Offer tips on buying homes and land properties. Send announcements about your seminars or group meetings to develop and expand your business.
2. Send an ecourse with tips on buying homes:
To be honest most people don't know anything about buying and selling properties. They'd love to receive some honest pointers from you. Compile all tips you know that are useful to your clients or potential buyers into an ecourse and send them as 7 day or 10 day ecourse.
3. Lists of local rentals:
While signing up ask your subscriber to select the infomation they want to receive. Some people are interested in renting condos and some like to share the rent with others. Try to divide your list according to your criteria. Send emails based on their interested information.

4. Get more leads:
Post some videos on youtube or create squidoo pages or hub pages. Post articles on content sites. Use your autoresponder form on all these areas to get more and more leads. More the subscribers/leads more will be your targeted prospects and potential buyers.
Install Wordpress blog on your site and post articles there. Invite your subscribers to leave comments on the topic. This way you can know what people are thinking and present trend.
Good luck!