Official sites of owncloud: http://owncloud.org
OwnCloud is an open source software. The Server software and PC clients are free. Android Client charges HKD6.68 in Google Play (Sep, 21, 2012)
It is a DropBox in your own server. Installation is simple. It can syn your files in your hard drive. Many other apps can be added.
Installation Guide
http://owncloud.org/support/install/
Platform: Ubuntu Server 12.04.1 LTS with LAMP installed.
owncloud version: 4.5.0
Install owncloud with aptitude with the following command.(sudo apt-get install owncloud) It will install owncloud 3.0
change to the root directory of web server (cd /var/www/)
Download owncloud 4.5.0 (sudo wget http://mirrors.owncloud.org/releases/owncloud-4.5.0.tar.bz2)
To be continued.