Google has just launched a free mobile website building tool as an extension to its existing Google Sites service. Like its big brother, which is designed to let anyone create a professional, template-driven webpage in minutes, the new mobile service is just as painless to use.

It’s also completely free.

While anyone is invited to try out the new service, it’s clearly being pitched to the SMB crowd, with pre-built templates for restaurants, local businesses, lead generation, eCommerce and one called “Social,” which lets your customers engage with your business on Facebook, Twitter, YouTube and other social services.

If none of the included templates suit your particular needs, a “custom” template is also available.

Adding text to the website you create is as easy as creating a document – there’s no HTML code required. Integration with Google Checkout is provided through the eCommerce template and traffic on all sites can be tracked through Google Analytics.

There isn’t a whole lot of customization you can do on these basic websites beyond adding text and choosing a background color, but, for many businesses, something basic is “good enough” to meet their needs, especially when the alternative is not having a mobile site at all.

For those already happy with their current desktop-sized website, there’s no need to switch over to Google Sites entirely for both desktop and mobile. The mobile sites service works as a standalone product. It can be your mobile site in addition to a separate, professionally designed main website or it can even be your only site, if mobile is all you need.