Jenv: nice little Java IDE (coded in Java, of course). Haven’t messed with it much, though, as I’m very happy with EditPad Pro from JGsoft (took a little while, but now I have syntax highlighting set up on every sort of file I code. It also has a customizable ‘tools’ menu so you can pass your code through compilers or other external programs. Maybe it’s not quite a true IDE, but it’s certainly a fine text editor).