Good article on Eclipse Development Projects

I've found a very decent list of excellent Eclipse development projects from this link at eweek.com.
To make it easy to read, I've extracted part of the content here.

Eclipse Modeling Framework (EMF)
Eclipse is huge in the modeling community. EMF is the core framework and code generation facility that allows developers to create applications based on a structured data model.
Xtext
Xtext is a relatively new project but is quickly become very popular for creating domain specific languages. With Xtext you can easily create your own programming languages and domain-specific languages (DSLs). The framework supports the development of language infrastructures including compilers and interpreters as well as full blown Eclipse-based IDE integration.

Jetty
Jetty is an open-source project providing an HTTP server, HTTP client and javax.servlet container. Jetty is a very popular Web server and servlet container. It is often found embedded in applications such as Yahoo Hadoop Cluster, Google AppEngine and Zimbra. Jetty provides a Web server and javax.servlet container, plus support for Web Sockets, OSGi, JMX, JNDI, JASPI, AJP and many other integrations

CDT
The CDT Project provides a fully functional C and C++ Integrated Development Environment based on the Eclipse platform. CDT is now the defacto C/C++ IDE in the non-Microsoft world. Most embedded vendors and Linux distros use CDT as their C/C++ IDE.
PDT Eclipse PHP Development Tools
The PDT project provides a PHP Development Tools framework for the Eclipse platform. This project encompasses all development components necessary to develop PHP and facilitate extensibility. It leverages the existing Web Tools Platform (WTP) and Dynamic Languages Toolkit (DLTK) in providing developers with PHP capabilities. PDT has quickly become the one the more popular IDE in the Eclipse community.
Mylyn Framework
Mylyn is the task and application lifecycle management (ALM) framework for Eclipse. Over the last three years Mylyn has become the hub or integration point for many of the Agile ALM vendors. Mylyn has over 45 different connectors that make it possible to link different ALM tools to its unique task perspective.
BIRT—The Business Intelligence and Reporting Tools
BIRT is an open-source, Eclipse-based reporting system that integrates with your Java/J2EE application to produce compelling reports. BIRT provides core reporting features such as report layout, data access and scripting. BIRT has become a popular reporting solution for Java developers.

Web Tools/Java EE Tools/Eclipse Java Development Tools (JDT)
Eclipse continues to be the standard for Java developers. If you are creating Java applications chances are you are using some combination of the JDT and Web Tools or Java EE Tools project.

Eclipse Plug-in Development Environment (PDE)
The Plug-in Development Environment (PDE) provides tools to create, develop, test, debug, build and deploy Eclipse plug-ins, fragments, features, update sites and RCP products. PDE also provides comprehensive OSGi tooling, which makes it an ideal environment for component programming, not just Eclipse plug-in development.

eGit Version Control
The rest of this list highlights up and coming projects that have become popular with developers. One of them is eGit, which is an Eclipse Team provider for the Git version control system. Git is a distributed SCM, which means every developer has a full copy of all history of every revision of the code, making queries against the history very fast and versatile. The eGit project is implementing Eclipse tooling on top of the JGit Java implementation of Git. Git is becoming a very popular source code management system. eGit is a new Eclipse project to provide tight integration between Eclipse and Git.

Gemini
The Enterprise Modules Project—Gemini—is all about modular implementations of Java EE technology. It provides the ability for users to consume individual modules as needed, without requiring unnecessary additional runtime pieces. Gemini implements many of the OSGi Enterprise Specifications.

Memory Analyzer (MAT)
The Eclipse Memory Analyzer is a fast and feature-rich Java heap analyzer that helps developers find memory leaks and reduce memory consumption. Memory Analyzer is becoming a very popular tool with Java developers.

Connected Data Objects (CDO)
CDO is both a technology for distributed shared EMF models and a fast server-based object-relational (O/R) mapping solution. With CDO you can easily enhance your existing models in such a way that saving a resource transparently commits the applied changes to a relational database. CDO is a model repository for EMF models. It provides the scalability and transactional capabilities required to use EMF for large scale applications. CDO has a 3-tier architecture supporting EMF-based client applications, featuring a central model repository server and leveraging different types of pluggable data storage back-ends like relational databases, object databases and file systems.

Eclipse Device Software Development Platform (DSDP) Project
The Eclipse Device Software Development Platform (DSDP) Project is an open source collaborative software development project dedicated to providing an extensible, standards-based platform to address a broad range of needs in the device software development space using the Eclipse platform. DSDP is a top-level container project that includes several independent technology sub-projects focused on the embedded and mobile space. Sub-projects under the DSDP include Blinki, Device Debugging, Mobile Tools for Java, Native Application Builder, Real-Time Software Components (RTSC), Sequoyah, Target Management, and Tools for Mobile Linux.

JavaScript Development Tools
The JavaScript Development Tools provide plug-ins that implement an IDE supporting the development of JavaScript applications and JavaScript within web applications. It adds a JavaScript project type and perspective to the Eclipse Workbench as well as a number of views, editors, wizards, and builders.

Eclipse Marketplace
The Eclipse Marketplace, which offers the Eclipse community a convenient portal to help users find open source and commercial Eclipse-related offerings. The new Marketplace client makes it easier for users to download and install tools from Instantiations and others.

I think these books about Eclipse are very useful....