Databases: Do you use them to aid in prospect management?

I was just wondering if anyones real estate firm uses databases to help tract prospective clients or to keep in touch with past clients in order to maintain a relationship with them to encourage repeat business. I know that I have so many people who call me once to ask a question on one of my listings that I don't hear back from and I was wondering if I had all of those contacts in a database if that would help me bring a few of those one time calls to the table!!!  I am interested in hearing your thoughts!!!