Neo4j is an open source graph database, storing data in the nodes and relationships of a graph.

An intuitive graph-oriented model for data representation. A disk-based, native storage manager completely optimized for storing graph structures for maximum performance and scalability. Neo4j can handle graphs of several billion nodes/relationships/properties on a single machine and can be sharded to scale out across multiple machines. A powerful traversal framework for high-speed traversals in the node space. Can be deployed as a full server or a very slim database with a small footprint (~750k jar). A simple and convenient object-oriented API.

Unlike twitter's FlockDB, neo4j can handle multiple levels of hierarchy. However where FlockDB is better is it's low latency, high throughput and inherent distributed nature.

"Phonegap is a HTML5 app platform that allows you to author native applications with web technologies and get access to APIs and app stores."

Hedgewars is a free open-source game based on the Worms series. Hedgewars is cross-platform and runs on Windows, Linux, Mac OS X, iPad, and iPhone (now that's just amazing)! Where this style game gets really fun is multiplayer. You can play against an AI team, against another player on the same computer, or online. Growing up I remember playing hours after hours of rounds of Worms with @PatrickMcKenna. That I can play cross-platform, online, on an actively developed game, is awesome.

Well what are you waiting for? Visit www.hedgewars.org and play it today!

This is the story of an underdog open source media player, trying to make it big in a world of default media players, with the single goal of being the best media player in the world. Cameos include Windows Media Player, Quicktime, Winamp, iTunes and many more. VLC promotional video by Adam Vian.

"An open source software involvement engine. For developers, we provide tools to demonstrate and broaden their experience and expertise in the open source community. Our vision is to make the open source community better connected, more productive, and ultimately well rewarded for its expertise."

Great little site if your looking to contribute to an open source project, but your not sure what you want to work or how to get started.

"RecordMyDesktop solves the screencasting problem Linux users have faced for a long time. RecordMyDesktop creates high quality recordings of your screen with or without sound. While it is a terminal application, when paired with gtk-recordMyDesktop, a graphical frontend for recordMyDesktop, recordMyDesktop becomes a robust tool for easily creating screencasts. RecordMyDesktop can be tweaked to your heart's content by changing the sound and video quality, frames captured per second, mouse cursor style, compression, and whether to record the current window or the entire desktop."

First heard this on Floss Weekly. Dynamic DNS, File-sharing, iTunes Streaming, VPN and over 260 one-click install apps (such as Wordpress, Drupal, Torrents, Jinzora, phpMyAdmin and more).

"Meld is a visual diff and merge tool. You can compare two or three files and edit them in place (diffs update dynamically)."

"A simple mission: To create an simple open-source, non-linear video editor for Linux."

One of the simplest linux video editing apps I've come across. Render time seems to be far greater than kdenlive's.

"Clonezilla is an open source, Linux-based alternative to commercial disk cloning tools like Symantec Ghost and Acronis True Image."

"Tornado is an open source version of the scalable, non-blocking web server and tools that power FriendFeed. The FriendFeed application is written using a web framework that looks a bit like web.py or Google's webapp, but with additional tools and optimizations to take advantage of the underlying non-blocking infrastructure."

"Back In Time is a simple backup tool for Linux inspired from “flyback project” and “TimeVault”. The backup is done by taking snapshots of a specified set of directories."

"Free and opensource tool for making diagrams and GUI prototyping that everyone can use. Also available as a firefox extension"

Alternative to BaseCamp - open source self-hosted project management CMS built on drupal

"Ubuntu Tweak is an application designed to make configuring Ubuntu easier. It provides many useful desktop and system options that the default desktop environment doesn't easily provide. It also offers easy installation of popular programs and 3rd party repositories."

Highlighting top 10 free applications available to make your PC into a Live Studio including AvideMux, Cinelerra, Kino and many more.