The doors of restaurants and barbershops are increasingly plastered with stickers touting various online rating services, from Yelp and Citysearch to the distinctive red crest of Zagat.

Now Google wants some of that door-panel real estate.

The Internet search giant is mailing out special decals to more than 100,000 small businesses across the U.S. which have been identified as Google Favorite Places.

The stickers feature a special bar code. Snap a photo of the bar code with your smartphone camera (such as an iPhone or Google’s own Android-based phones) and you’re automatically served-up reviews and other information about the particular merchant.

It’s all part of Google’s ongoing quest to lure local businesses onto the Web (and consequently, to make money selling ads when web surfers search Google for information on those local businesses).

The plan has some interesting and intriguing possibilities in terms of connecting the brick-and-mortar world with the virtual world. Let’s just hope merchants have room left on their doors for another sticker.