Eclipse

I just started to play with eclipse. I must say it's very cool. Of course, most of the interesting ideas in Eclipse have been seen before in Emacs/XEmacs (and even in some commercial IDE's). But a few interesting things about this are:

1. It's open source.
2. Supported by IBM.
3. Written in Java, so lots of people can expand it/learn from it.

Of course, I'll probably just continue to use vim...