Eclipse plug-in development = an architected means of extending the Eclipse environment, whether it be the IDE itself, or an application based on Eclipse (also known as "rich client platform" applications).
The eclipse whitepaper is a good introduction to the whys and what-fors of plug-in development.
Co-author of <a href="http://www.jdg2e.com" target="_blank" rel="nofollow">The Java Developer's Guide to Eclipse</a>, 2nd Edition<br />(Yahoo group <a href="http://groups.yahoo.com/group/JDG2E/" target="_blank" rel="nofollow">JDG2E</a>)
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com