Buying Apps in the Google Cloud Here are some must-have apps for small businesses.

It's Google's world--the rest of us just work in it. Beyond the digital services giant's increasingly ubiquitous search, mapping and advertising solutions, it also has emerged as a leader in cloud computing: More than 2 million businesses have adopted the Google Apps suite, which promises firms a cost-efficient and hassle-free alternative to Microsoft Exchange or Lotus Notes.

Growing demand for enterprise software outside of Google's fields of expertise prompted the March introduction of Google Apps Marketplace, an online storefront aggregating cloud applications from more than 50 third-party allies. Given the volume and breadth of applications available, comparison shopping in Google Apps Marketplace can be challenging. Here are some must-have apps for small businesses.

BatchBook Social CRM Organize contacts, view customers' social networking activities and track leads all in one place with BatchBook Social CRM, a customizable, web-based contact relationship manager that synchronizes with existing Google contacts to more effectively keep tabs on all of your business relationships. Prices start at $9.95 per month.

OffiSync This Microsoft Office 2003, 2007 and 2010 add-in extends core Word, Excel and PowerPoint functions via collaboration capabilities powered by Google Docs and Google Sites. With the free OffiSync application, users can maintain the familiarity and comfort of Office while leveraging Google-based web solutions.