The latest Eclipse is superb in its java tooling, especially for large projects - great refactoring abilities, class hierarchy visualization, navigation, ant integration, plugins available for Checkstyle and Findbugs, etc. It's also a lot more stable and robust than I had expected for such a large IDE - I've had no real problems with it so far.
A much-underrated feature is the Mylyn task-focused programming system, which reduces information overload and saves you a lot of time repeatedly navigating around hierarchies and files. I've seen nothing comparable in any other editor.
There is also some great integration into bug tracking systems. My projects use Bugzilla, and I almost never need to visit the slow bugzilla web interface or wade through bugmail emails anymore - bug search and details, comment posting and bug change notifications are all right there in the Mylyn task list.
Before switching to Eclipse when the 3.5 release came out, I previously did all my Java work in jEdit, which I still use for other languages; I hate to think how much time I wasted by manually doing the tedious tasks that Eclipse could have automated for me.
I concede that you do need a fast machine, lots of memory and plenty of screen space, but it's well worth it for the time savings on the tasks for which it is suited.
I use Eclipse for java and xml, falling back to jEdit (which I used exclusively for several years) for pretty much every other file type.
jEdit is great for its impressive range of language syntax highlighting support, large selection of small and useful plugins, good search/replace features, and ease of writing your own syntax highlight modes, recording macros, etc. As others have said, it has the power of emacs or vim, and everything is customizable, but it lacks any substantial barrier to entry.
It also has the advantage that you can use the same user profile on multiple platforms (e.g. linux/windows) - before I ditched my Windows machine I ran like that, rsync'ing everything to/from linux at work.
The nice thing about Jungledisk is that you can just mount the thing as a directory (uses fuse under linux) and use rsync to do the backups. That works well for me with multi-Gb source repositories, whereas when using Mozy on windows, its built-in scheduled backups struggled badly and chewed a lot of CPU, presumably scanning through all the thousands of files.
That's not really a fair comparison - I haven't tried Jungledisk's built-in scheduled backups, merely using it as a mounted drive and doing the backups manually with rsync. But that's too bad - last time I looked, Mozy didn't support mounting as a drive, or even linux.
By far the worst: on site doing commissioning / systems integration testing of warehouse automation systems - cranes moving pallets around, boxes trundling on conveyors, etc.
The automated equipment we were debugging (and volume testing with things moving around continuously) was the least of it... the huge site was still under construction. All around me there was racking being cut and welded, electricians installing stuff, aromatic concrete floor sealant being applied, various random drilling and banging.
I had to write large amounts of new code on the spot as we found problems (missing features, mostly) during testing, while the automation engineers stood around annoyed and waiting.
When I first got to the site, I didn't even have a laptop - had to lug a desktop PC and CRT monitor there and back every day (carrying it across half the site and the loading dock) for the first couple of weeks. For part of the time, this involved carrying it across iced concrete, since it had been snowing.
Oh, and there was the engineer from one of the third-party equipment suppliers, an Italian company - nice chap but he didn't speak very good English; the noise level didn't help the already poor communication, and when we started our testing, we discovered he had developed his control software from an interface specification three versions old and half a year out of date.
I have a Stokke Balans Duo chair which is the most comfortable thing ever, and perfectly suits someone who both wants to move around restlessly, lean forward to type, lean back to think... used daily for 8 years and it's bulletproof.
A much-underrated feature is the Mylyn task-focused programming system, which reduces information overload and saves you a lot of time repeatedly navigating around hierarchies and files. I've seen nothing comparable in any other editor.
There is also some great integration into bug tracking systems. My projects use Bugzilla, and I almost never need to visit the slow bugzilla web interface or wade through bugmail emails anymore - bug search and details, comment posting and bug change notifications are all right there in the Mylyn task list.
Before switching to Eclipse when the 3.5 release came out, I previously did all my Java work in jEdit, which I still use for other languages; I hate to think how much time I wasted by manually doing the tedious tasks that Eclipse could have automated for me.
I concede that you do need a fast machine, lots of memory and plenty of screen space, but it's well worth it for the time savings on the tasks for which it is suited.