Less known but useful features in Eclipse

The plugin Spy (Alt+Shift+F1) is certainly one not very advertised.
Yet if you have any question about "how I develop a feature X looking like the one in eclipse", it can be very useful to quickly locate the right eclipse java source which does implement that feature!

_{(source: willianmitsuda.com)}

See also this Guide to eclipse3.5:

The Plugin Spy gives you easily information about the running UI.
Press Alt+Shift+F1 to get information about the current running Eclipse plugin / data types / screen.
This way you can get immediately access to the plugin which is currently running.

_{(source: vogella.de)}

Eclipse 3.5 introduced the possibility to check which plugin contributed a menu. Press "Alt+Shift+F2" and select a menu to see who is contributing this menu

_{(source: vogella.de)}