I have been looking for some source on Bulk upload tool but find this small tools that can help while uploading multiple document to some document library in SharePoint 2003. See blow
Stuart Preston’s Blog
Some while ago now, I wrote a tool to automate the uploading of an entire folder and subfolders into a Sharepoint/Windows Sharepoint Services Document Library. It uses some simple WebDAV calls to do all the uploading/folder creation. I’ve tidyed it up a little, and put a link to the file below in case anyone else finds it useful.
Note: If run repeatedly, the documents are overwritten in the target document library, so be careful! Of course, the tool runs in the context of the calling user, so you need to ensure you have the relevant rights in order to create the remote files/folders!
Download here: http://blogs.conchango.com/stuartpreston/files/spsbulkupload.zip
Jerry Yasir's Blog 
it worked but is there any way to specify filename (with wildcard)?