I often switch between using IntelliJ IDEA and Eclipse for my day-to-day development tasks. One reason this is possible is thanks to a set of key bindings that allow me to use the IntelliJ keyboard shortcuts in Eclipse.
eclipse-intellij-key-bindings.java contains a set of key bindings for Eclipse. These can be imported into Eclipse by opening the preferences import dialog (File > Import > General > Preferences). I've used these successfully with Eclipse 3.x but have not tried with earlier versions of Eclipse.
The key bindings were originally posted (and created?) by Stuart Ervine in an entry in his abandoned jroller blog. Any and all credit goes to the original author for this work, I'm just mirroring it here to make sure it doesn't get lost in the Interweb.
(April 12, 2010): Fixed the broken link to the key bindings file. A very belated thanks to James Strachan for pointing out that it was busted...