The Background Intelligent Transfer Service (BITS) Server Extension lets you configure IIS Server to allow BITS clients to perform background restartable uploads of files to IIS virtual directories. Upon completion of a file upload, a Web application can be notified of the new file (via a POST to a configureable URL) in order to process the uploaded files. Your Web application can then optionally reply to the client's posting.
Other configurable options include: setting limits on uploaded file size; automatically deleting incomplete files after a preset amount of time (deleting orphan files); and server farm support.