ArgoUML

Open Source UML Modeling Tool

The self-proclaimed "leading open source UML modeling tool" supports diagram editing for all 9 UML 1.4 diagrams and comes in 10 different languages. Because it's based on Java, it runs on any platform, and it can export diagrams in 6 different file formats - GIF, PNG, PS, EPS, PGML and SVG. Another nice feature is that it supports reverse engineering with Jar/class file importing.

PhoneGap

Open source Mobile Framework

PhoneGap is a free and open source framework that allows you to create mobile apps using standardized web APIs for the platforms you care about. It enables software programmers to build applications for mobile devices using JavaScript, HTML5 and CSS3, instead of device-specific languages such as Objective-C.

Sencha Touch

Mobile Application Framework

Sencha Touch, a high-performance HTML5 mobile application framework, is the cornerstone of the Sencha HTML5 platform. Built for enabling world-class user experiences, Sencha Touch is the only framework that enables developers to build powerful apps that work on iOS, Android, BlackBerry, Windows Phone, and more.

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.