Last week I wrote some code for migrating a networkdrive folder content into a SharePoint Library. You cannot use the Lists.asmx for uploading the documents because this webservice does not provide the functionality for uploading files. But after a little bit of research I found quickly that you can use the copy.asmx webservice. Normally it is used for copying files between two SharePoint Libraries but it also work for copying files from a networkdrive into a SharePoint Library. So you can use the code behind for copying a file on a network drive in a Sharepoint Library.