OwnCloud

OwnCloud is free and open source software that operates as a very simple way to set up your own syncing, Dropbox-like cloud storage system on your own server or web site. It's quick and easy to set up, and doesn't require advanced technical knowledge. OwnCloud allows people to make and share their own apps that run on ownCloud including text editors, task lists, and more.

Seafile Cloud Storage

File Syncing and Collaboration for Teams

Seafile helps you with: File syncing and sharing – You can organize files into libraries. Each library can be shared between users and into groups. Team Collaboration – Edit and comment files online. Seafile offers messaging, group discussion, activity notification and file versions.

WikiCalc - Open Source Spreadsheets

wikiCalc is a web application, created by Dan Bricklin, that allows for the creation and editing of spreadsheets through a wiki-style user-editable interface. It is currently released as version 1.0 for use on Windows, Mac, Linux/Unix, and other platforms that can run the Perl language.

KSpread - Open Source Spreadsheets

KSpread is a fully-featured calculation and spreadsheet tool. Use it to quickly create and calculate various business-related spreadsheets, such as income and expenditure, employee working hours.