The more I use the combo LaTeX and Emacs, the more I like them. It is amazing how much complexity they have below their surface and how much they can accomplish. Unfortunately, I still don't know enough to call myself neither a LaTeX literate nor a Emacs literate, but I sure hope to fill the holes in my education soon.
One package that I recently discovered for Emacs is ECB, which provides many of the features found in other development programs, like Microsoft's Visual Studio. And the included speedbar (and the newer speedbar-beta, already included in Debian's sarge is amazing.