Owncloud

Install:

git clone https://github.com/owncloud/core.git owncloud
cd owncloud
git submodule init  # 3rdparty directory
git submodule update

There's a command-line tool for administering it:

sudo -u www-data php5 occ

Use this for upgrading point releases, adding/managing users, apps, etc. May need to disable non-core apps to do upgrades.