Many people use Microsoft SharePoint regularly.  You click on a document and up pops MS Word or several other tools that are WebDAV compliant.  Most systems have standard authentication so you get a username, password challenge and now MS Word stores directly to the server and can do neato things like checkout the document so no one else can modify until you checkin.

There is a little slight of hand going on here.  On most sites if you click on a document you get a download to your machine that you may open directly.  The server does download the document to a temp space and Word opens the file in your temp space.  There is no connectivity to the server, no save to server, checkout, etc…

To do this you can use either an activex control or a shared web folder.  But you didn’t do either of those things, so how did it work?

It turns out if you installed MS Office 2003 or later or even a version of IE in the last several years you did install an activex control called OWSSUPP.DLL onto your machine.  It is a full blown activex control that lets sites that know about it, SharePoint and others, to code something like: activexControl.editDocument(http://server/document.doc) in the HTML page that gets sent to you.  And tada! Word opens, sees a web address for the document being opened and it asks the server, are you webdav, and you are off and running.

The activex control is called Microsoft SharePoint Client Support.  Since SharePoint appears to follow the webdav standard pretty closely you can take advantage of it and use it on your webdav server.  Generate a web page with an onclick event that calls upon the activex control to invoke your webdav server.

Of course this is limited to MS Windows clients running IE, but that is usually the biggest audience to begin with.