If you also use Google Docs for creating, accessing, and storing documents, OffiSync is for you. It lets you take advantage of the collaboration and online accessibility offered by Google Docs, while working in the familiar Microsoft Office applications.
You can access your documents from Google Docs right inside Microsoft Office, and you aren't confined to using the Google Apps.
Keep in mind that Microsoft included similar integration in Office 2010 for its online storage service, SkyDrive from Windows Live.
However, OffiSync is available for Word, Excel, or PowerPoint in Office 20032010.