Syncthing is a continuous file synchronization program. It synchronizes files between two or more computers in real time, safely protected from prying eyes. Your data is your data alone and you deserve to choose where it is stored, whether it is shared with some third party, and how it's transmitted over the Internet.
Github: https://github.com/syncthing/syncthing
Official APT repository: https://apt.syncthing.net/
A F/OSS alternative to Dropbox. Also seems to have some wiki functionality available. Written in Vala.
A personal storage server for storing blobs of data. Basically a dumptruck for posts, files, and whatnot. Search, browser, and visualize. Can be mounted as a file system using FUSE. Can back up socnet data. CLI and web UI.
Github repo: https://github.com/perkeep/perkeep