Ready? The next big thing in casino marketing is... email.

Last month, I got an email promotion from Harrah's (NYSE:HET) St. Louis. Just print out the email, I was told, be among the first 2,000 to show up on March 4 (a Thursday) between 8:00 a.m. and 8:00 p.m., and receive a free Little Rascals bobble head doll.

Now, I'll admit, I was skeptical. Just a couple of months earlier, I drove by Harrah's Tunica near Memphis, where a billboard announced the casino was giving away free six-packs of Coke (NYSE:KO) to guests checking in at the hotel. Weird. But at that moment, I saw some merit to the email-only bobble head promotion. And it has nothing to do with its auction value on eBay (NASDAQ:EBAY).

Please, let me explain.

Virtually every locals casino in the country mails out coupon sheets on a monthly basis to anybody that has signed up for a player's card -- or pretty much any person and address they can get their hands on. Usually, these sheets contain coupons for such things as match plays, plain old cash, raffle entries, or discounts on hotel rooms. That kind of promotion can be expensive.

But a few months ago, I registered my Total Rewards card and email address at Since then, I've been getting regular emails detailing casino events, a monthly schedule for the discounted room rates I qualify for, and other information. As you can see, the possibilities are endless: When Harrah's St. Louis reopens its new poker room, I'm sure I'll be the first to know (along with 50,000 of my closest email friends). And when it begins its weekly poker tournaments, I'll bet on getting an email.

And here's the real beauty of it: The marginal cost of advertising to more and more people via email should be next to nothing!

Now, this bobble head deal was fairly small scale and local to St. Louis. I'd be impressed if 2,000 people actually showed up to pick up their Little Rascal (according to the property's promotions specialist, they sold some of the bobble heads to other Harrah's properties, which then gave them away). Rather, I'd imagine that Harrah's St. Louis was trying to gauge how effective its email marketing really is, or how effective it can be.

Though I'd venture that Harrah's probably has the most effective email-marketing program thus far, it is not alone. Virtually every casino operator has some sort of online registration capability for their rewards program, including Harrah's riverboat competitors Ameristar Casinos (NASDAQ:ASCA) and Argosy Gaming (NYSE:AGY).

This saves money and is just plain smart business. You can bet that these companies will make greater use of email for their marketing in the near future -- at least, the smart ones will.

Ever get an email from a casino? Let's hear about it on the Gamblin' Fools discussion board.

Fool contributor Jeff Hwang owns shares of both eBay and Ameristar Casinos.