Add canned responses and snippets to Microsoft Outlook with Text Lightning
And Text Lightning doesn't stop with mere text. It supports other file types, so you can stash commonly attached images, documents, and spreadsheets in its sidebar as well. There's also a built-in forgotten attachment detector and quick move button for zapping messages into your archive folders.
Version compatibility isn't spelled out on the Xequte website, but it worked well for me in Outlook 2003 and Martin at ghacks had success with Outlook 2010 -- so we fully expect Text Lightning also works with Outlook 2007.
Download the Text Lightning add-in for Microsoft Outlook