Harmony Outlook sidebar provides full featured access to documents within Sharepoint libraries. Using the Harmony sidebar documents in email attachments can be dragged to Sharepoint libraries and documents from Sharepoint libraries can be added as attachments or as links to emails. To cap it all Harmony Sidebar is Free!!!
Once the Harmony side bar is installed and the Sharepoint connection is setup, Sharepoint documents will be available in the side bar. Below screen shot shows contents of document library within the Harmony side bar
Harmony Sidebar for Sharepoint can be downloaded from http://harmony.mainsoft.com/content/downloads/harmony-for-sharepoint