It has been more than a year since my original posting (‘Filesystem for large USB storage devices?’), but the issue still exists. I did some research on this topic and found the following relevant links:

• There has been a patch for ext[234] floating around since 2012 that would introduce mount options to enforce UID and GID similar how it already exists for vfat mounts. LWN has an article on this topic: http://lwn.net/Articles/497106/
  Here is the discussion LWN is referring to: http://thread.gmane.org/gmane.comp.file-systems.ext4/32276/
  I wonder why nothing more happened here. There were some nay-sayers which seem to discourage the original patch author and eventually choked the discussion. Great job, guys :-P

This blog post shows how to setup a personal WebDAV/HTTP server which shares a directory inside your home. It is designed for local networks, but as security (SSL and username/password) is part of the configuration, you could give friends across the Internet access to the server.