rebelutionary
Mike Cannon-Brookes writes that you cant really see all the benefits of IDEA untill you've tried it for a while.
I agree. I discover new stuff everyday. This is the only program where I leave the hints on.
If you're doing Ant files for example it is intelligent enough to mark unknown properties as red. Add a Property tag to import an outside properties file and it picks it up straight away.
The XML editor is also absolutely amazing.
I also only recently discovered the joys of ctrl-clicking, which hyperlinks any identifier and goes to it's source.
At my office here almost everyone is sold on it now and people shout out "Did you know that IDEA can do ..." all the time at the moment.