Folks have mentioned Eclipse as an IDE, but there's also Eclipse as a platform. I have three Eclipse RCP apps I use for visualization daily.

I also manage a lot of equipment that requires java webstart to load a configuration GUI to accomplish tasks that would be darn near impossible at a CLI or any other way.

I logged into Cisco TAC the other day. Requires Java for ticket management tasks.

I use some rf propagation tools for a hobby that are java apps.

I make frequent use of Deskzilla. Java app.

I could go for days. I won't.

Do IDEs count? A lot of Mac users use Eclipse. It's not common among all-Mac teams that just do XCode, but it's fairly common for devs in groups that mostly do PC development to own Macbooks that they run Eclipse on.

Probably not a big concern for Apple, but it's common in universities, too, since Eclipse is (until now, at least) cross-platform enough that you can assume Windows/Mac/Linux-using students can all install it on their laptops.

Encyclopedia Britannica.

Vuze aka Azureus