I've been annoyed slightly (not an unfamiliar feeling for me, when it comes to technology) by the Internet Explorer WebFolders. More specifically how they work in SharePoint 2007 (and possibly other versions).
What I've always wanted was the ability to view several document libraries in Explorer View on the same page, and be able to drag stuff between them. As an added treat, I've wanted to see the folder tree as well, and possibly even navigate up a notch to see the explorer view of all folders.
Being annoyed for a while, I recently implemented this as a custom ActiveX control. Admittedly not something suited for public portals, since ActiveX installs are generally seen as a security risk. For intranet portals, on the other hand, where Internet Explorer is a possible requirement in either case, it's a nice addition to the functionality stack.
Here's a quick demonstration screen cast of the ActiveX in action, with two doclibs shown on top of each other: http://www.screencast.com/users/einaros/folders/Jing/media/8dff717a-7de1-4cd6-95dc-f4a371b5769c.
It supports file / folder filters, to hide built-in SharePoint content; specification of a custom root folder, e.g. showing "My Computer" as base of the tree view, or making the root of a SharePoint web appear to be the root; and a bunch of other stuff.
Is this of interest of anyone, or am I on my own to see potential here?