What about "https://owncloud.com/registration"; ?
It is a server using the owncloud.org system: "About ownCloudBased on the popular ownCloud open source file sync and share community project, ownCloud Inc. was founded in 2011 to give corporate IT greater control of their data — combining greater flexibility, openness and extensibility with on premise servers and storage. Company headquarters are in Boston, with European headquarters in Nuremberg, Germany." - https://owncloud.com/about
