If you write code, and you haven't tried Eclipse, you haven't experienced a truly great IDE. I'm currently trying to set it up to do my Web development, Java Development, and if I can figure out how to get a compiler to work, C++ development (that will be last, since I don't have any @home C++ work to be doing... I get enough of that at work). (I'm going to update this post as the IDE setup continues. I'll actually get links to the plugins shortly)
The following currently makes up my IDE:
Eclipse, while focused on Java, is extremely flexible as to support almost any kind of development you can think of! Anyway, enough gushing. I think I've finally setup Eclipse to be my primary web development IDE (trying to replace Dreamweaver, which has enough frustrating quirks of its own to really get on your nerves). I finally figured out how to do FTP syncs with a web host. The only think it doesn't have is a WYSIWYG editor in addition to the code view. While I mostly work in the code view, I do find that when I'm doing table entries, visual entry is usually a lot quicker and less error prone).