I would also recommend to try Q-ImageUploader which is a multiple files uploading Flash component and allows to:
- resize/compress/rotate images on the client side befor uploading to server
- generate preview
- add watermarks
- add tags, descriptions, album names to photos
- highly customizable with software or with XML
It has PHP and ASP integration examples.
Now it also has Free Flash Files Uploader wich is very useful and easy to integrate and of course free.