Except for occasional Common Lisp development (Emacs!), I just about live in an IDE. For the most part this is the excellent NetBeans 6.0 with Ruby support. However, I have dozens of existing Java projects and they almost all are IntelliJ projects so I will be using IntelliJ as long as I need these projects (long time!). To make this "IDE soup" even richer I am learning Scala (best development environment appears to be the Eclipse plugin) and experimenting a little with Google's Android portable device platform (again, an Eclipse plugin).
It takes me a minute or two to really get into a different IDE when I change tasks - makes me nostalgic for the 1980s and 1990s when I lived in Emacs for programming, email, shell, and usenet. While there are interesting Emacs tools for Android, Ruby, Rails, Java, and Scala, I am not willing to go back in history and spend my days in Emacs.