Saw OwnCloud in the title, stopped by to say that it is EXCELLENT. One of the most exciting (new) packages to hit open source in many years. Some things I use mine for:
Syncing OneNotes across multiple devices - 2 PCs, a Mac and a phone.
Automatic file sync (with binaries for Mac, Win & Linux)
Publishing documents to clients
Contacts & Calendar sync across multiple devices
WebDAV file shares offer native access for Mac, Windows and Linux.
... In a seriously slick interface with fairly simple and flexible deployment.
Seriously, can't recommend it enough. This reminds me, I should get back to submitting my patch for LibreOffice Spreadsheet previews..