I created the Silverlight Multi File Uploader. It allows you to upload multiple files at the same time. The files are uploaded to a WCF webservice where they can be processed.
A nice feature is that you can see the upload progress of all your files. The control also has some handy configuration options, you can set the number of simultaneous uploads, the maximum file size etc.
The WCF webservice is included and easily extendible. There's 1 method you can override, it's the FinishedFileUpload() method. Inside the method the name of the file and the input parameters are available. By overriding that method, you can process your file, for example move it, link it to a database item, etc etc.
You can see the control in action here.