Dan, this is fantastic.
In addition to SOAP and OKI, we might want to start looking for WebDAV libraries that could be interfaced with file-storage. AFAIK, a WebDAV interface would enable folks who use KDE, Mac OS X, and Win2K/XP to mount file-storage directories on their desktops as if they were folders on a local drive.
Jakarta Slide has WebDAV built in but I have no idea how hard it would be to adapt their code. The same holds true for the W3C's Jigsaw server. You can get a list of all Open Source WebDAV implementations at http://webdav.org/projects/#opensource.
