Ok OK I know this isn't the high tech stuff I'm always using, but the truth is that hitting someone with a marketing message in several different fashions will get more results than depending on only one. I still love email because it is the cheapest and less risky of all, but post cards come next.
I sat in on Nancy Miller's mail to:firstname.lastname@example.org session at the National Speakers association and got my first taste of organized post card promotions. She showed me really innovative and inexpensive ways to get your message across with postcards.
I then got a course from Alex Mandossian http://www.marketingwithpostcards.com/ that filled in all the details.
I haven't done anything fancy yet, but I got immediate results just by sending out a plain black on blue cardstock postcard. I made it by cutting a regular sheet of cardstock in half whichgave me two postcards per sheet. I had it duplicated at OfficeDepot.
It immediately generated seminar attendees that just don't use their email as much as I do and at least one joint venture is coming out of it.
You can also use post cards to get the email address of people on your database. You could offer some incentive to sign up for your email newsletter so your marketing to that prospect is free from then on. Tapping your database is always valuable and postcards are a great way to do it.
If you would like to be on the snail mail list for my post card mailings leave your name and address at http://www.public-speaking.org/snailmail.htm (As always your information is never sold or rented.)