Google is the internet’s 800 pound gorilla when it comes to advertising, but that doesn’t mean that it has exploited all of the areas for growth potential. A significant one: small, local businesses.

While many small businesses use AdWords, or have given it a spin, even more aren’t using it. There are plenty of reasons why. Many small business owners find paid search challenging to set up and manage, and if not set up and managed properly, campaigns can be very costly and ineffective. One costly, ineffective campaign can potentially cost Google a customer for life.

One of the ways that Google is trying to lure small businesses into its customer ranks is through an offering called Google Tags, yellow markers which appear on Google Maps business listings and when rolled over, can highlight coupons, photos and other advertiser-supplied content.

Unlike Google’s cash cow, AdWords, customers participating in the Google Tags program aren’t charged per click. Instead, Google charges Tags customers a monthly flat fee of $25. That, in theory, makes pitching Tags to the mom and pop business down the street a more straightforward process.

To entice more businesses to sign up, Google is running a promotion this week. Through Friday, July 23, Google is offering a 30-day free trial of Tags to new customers. While free credits for new AdWords advertisers are widely distributed by Google and its partners, the fact that Google is running a promotion for Tags just might highlight a recognition that recruiting small businesses to AdWords is often a multi-step process. And one of the best ways to start that process is to hit business owners with a product offering that is easy to understand and has a fixed price.

There are millions of small businesses in the United States alone. And while Google could sign up a million of them at $25/month and still not do much for its bottom line, if Google can successfully graduate small business customers from offerings like Tags to AdWords, its may just find its second wind when it comes to revenue growth.

The key for Google, of course, is getting Tags customers, who don’t receive placement with their listing, to ask the question: “I love my listing, but how do I get it higher?” If it can do that, Google won’t have to worry about less-than-stellar earnings for a while.