I love SmugMug so much I wanted a really easy way to get my pictures from my hard drive to SmugMug. Enter Send to SmugMug. This application will install a little entry in your contextual menu for folder that says... "Send to SmugMug". When you select this, the contents of the folder (.jpg only) are displayed in a window that allows you to add them to an existing album, or to create a new album setting all the available options.
The Application and Source are available for download. Included is a Class Library that exposes most of the SmugMug XML-RPC API. I will release it when it's done, I have a few more methods to support. Once that happens you can plop this into your .NET app and program against SmugMug.