Eclipse users and developers know that the Eclipse platform is a bit of beast - there is just so much in there that if you don't get the chance to poke your head out of your own personal Eclipse-interaction light cone, you can miss out on some cool stuff. And it turns out that the best way to do that is to come to these kind of conferences :) Here's some things I found out about yesterday.
Plugin Spy
Select something in the UI, hit Alt+Shift+F1, and you get a window containing an introspection of the current widget/part that you have selected. Check out the PDE Incubator page, and a blog entry from Chris. If you are using Eclipse 3.4M2 or later, you will find this feature already built-in.
Clean Ups
I use Checkstyle in most of my project work, and it and I have an uneasy relationship. The sort of one where the dishes get broken and people come around to bring the pets away. I have always whined that if Checkstyle is so smart, why doesn't it get rid of that trailing space it spotted for me and stop bothering me? Well, it can't do that, but Eclipse Clean Ups can. Woot!
A Clean Up is just a collection of refactorings that you use regularly on your code to keep it squeaky. You can run 'em manually, or have them run automatically when you save a Java file. Go to this developerworks article to find out more.
EclEmma
If you are familiar with the Emma Project then you will have probably guessed that this is a test coverage tool for Eclipse, based upon Emma. I've always found test coverage to be an invaluable tool for showing you where the great, gaping, black holes of non-deterministic behaviour reside in your code. There's a lot of tools that can do coverage, and there are Eclipse integrations at varying levels of quality. What I liked about EclEmma is that it is quick and straightforward to use on a single Eclipse project, and gives me the results fast. Although the results are not always welcome :)
Update: Jeff McAffer's Eclipse Update Talk [pdf link] has details of Plug-in Spy and Clean Ups.