Improve File.Pizza via borrowing code from other similar projects, and listing said borrowings in the FAQ:
- Fram's F*EX, DOX, sexsend&sexget, WOOS, etc. - http://fex.rus.uni-stuttgart.de & http://fex.belwue.de/fex.html - it could be implemented as one of the fallback options of File.Pizza - it just needs a modern HTML5 web-browser + an email client (even CLI mutt will do...)
- http://toffeeshare.com - looks like a clone of File.Pizza but with a better GUI, QR-codes, and an optional non-p2p webserver relay as a backup option
- DC++/ADC & DC++/ADC hubs web-server software
- .torrent & .magnet (DHT, uTP), .metalink, .meta4 - http://metalinker.org
P.S. Currently, the https://file.pizza web-service didn't manage to send a 1 KiB .txt file, perhaps you should see what is going on, and whether NAT-traversal, iptables IP-address-blocking, and port-forwarding have anything to do with it...