Dear LazyWeb: What Are Good Web Based File Transfer Interfaces?

I’m working on a project at work to redesigning a 1997-looking application that customers use to securely send files back and forth with us, instead of using plain-text emails. I’m looking for examples of nice clear interfaces. I’d love to find a really clean looking AJAX implementation of something similar to show to my project team for inspiration. I know there are some limitations on what AJAX can do regarding accessing local files, but what’s out there, what have you seen that’s worth looking at for inspiration?