Java Tool: IntelliJ IDEA - Now open source

Java has many editors, both free and commercial. One of the best such tools is IntelliJ IDEA, and it is now Free as well as Open Source, with users no longer having to pay for it (learn more). From the site:

Community Edition — Free and OS Java IDE
Intelligent code editor has all the smarts for understanding Java code; provides refactorings, code inspections and intentions, super-fast navigation and search — all that we have accumulated over the years.
Integrates with such essential tools as JUnit and TestNG, Ant and Maven, and popular version control systems: CVS, Subversion and git.

Eclipse4SL

Microsoft Silverlight is a cross platform, cross browser and cross device plug-in that enables designers and developers to build rich media experiences and RIAs for the web. It significantly reduces development and deployment costs and provides enhanced Web audio and video streaming and playback using industry-leading Technologies.
The project has been submitted to the Eclipse Foundation and released as an open Eclipse project. Specifically, the project will be an Eclipse plug-in that works with the Eclipse Integrated Development Environment (IDE) and Eclipse Rich Client Platform (RCP) to provide both a Silverlight development environment and greater interoperability between Silverlight and Java, to facilitate the integration of Silverlight-based applications into Java-based web sites and services.
Located at this location (link)