I have been using Dropbox (http://www.dropbox.com) and Box.com (http://www.box.com) to share files with people.

Dropbox has great Linux support and integration into the Gnome Nautilus file manager.

Box is good too but is more Windows / Mac Centric and I think currently only supports access via the dav protocol in Linux.

They both AFAIK have Android clients.

They both are accessible via a web browser and I've installed both Google Chrome webapps for both services.

I've been sharing some files with Dropbox and getting SMS's from friends who get notified on their computers when files are changed by me. So pretty good visibility all people sharing a file if it changes with dropbox.