Universal Plug and Play (UPnP)
UPnP is a set of protocols to share media on the network. It is also supported by a wide range of Wi-Fi access points.
You also need a UPnP-client, which can be installed using sudo apt-get install djmount. UPnP discovery can be started using djmount mountpoint. After that you can use it like a local folder and add it to your local collection.
On Debian-based distributions like Ubuntu you can install a UPnP-server using sudo apt-get install ushare. The service is started in the terminal with the command ushare -n servername [-i interface] [-c folder]. You can also manage shares using the webinterface, which you can access by opening http://127.0.0.1:port/web/ushare.html in the browser. port needs to be adjusted to your settings.