I've started using Colligo for SharePoint which makes opening, editing, adding and savings documents to a SharePoint document library much easier. I've used Groove and Outlook, but Colligo is better. The main reason, it is more stable. Outlook kept crashing on me when I would preview a document, and it would slow my Outlook down. If you are like me, your email is critical, and so anything that slows it down or makes it crash doesn't work. Also with Outlook you can't add documents to a document library by drag and dropping them from windows explorer (major feature gap if you ask me). This is where Colligo drag-and-drop shines. Simple and reliable, I like it. Colligo offers a free version which gives you read-only access to a document library and a contributor version which they charge $125 for.