Although I've used Emacs for well over 10 years, and I've been a pretty serious Common Lisp programmer, I don't consider myself an Emacs power user by a long shot: I don't think I'm at all skilled in its use; I don't customize it very much; and I know almost none of the interesting bits of Emacs Lisp. The only applications I really use within Emacs are Gnus, the News and Mail reader (which I adopted after one too many "please find attached" errors) and, more recently, SLIME (but since much of my Common Lisp work is at the implementation level, the luxury of using SLIME for development is often unavailable.
Recently, though, I'm beginning to suspect that I might get more practice. Firstly, the additional responsibilities of a permanent job in UK academia (essentially boiling down to administration, lots of it) meant that my old strategies for managing my TODO list (scraps of paper, followed by writing in different colours on my office wall, followed when I ran out of wall space by a plain-text TODO.txt file) were no longer sufficient to manage the complexity, and I discovered org-mode.
My use of org-mode has, roughly, removed the feeling that I'm drowning in a morass of multiple different things to do with no idea of what's important or urgent along with a feeling that I've forgotten the really important things, and replaced it by a vague feeling of guilt that I'm not doing all the TODO, STARTED, WAITING items that show up in bold red in my *Org Agenda* buffer (and probably won't, ever). I haven't yet found a good way of integrating notes that I take on my often-disconnected laptop with the master org files kept on my server, but vague guilt is noticeably preferable to drowning, so this is a net win.
Also a net win for me is the new daemon functionality in GNU Emacs 23. My setup for mail is perhaps a little eccentric; I read all my mail, including work mail (over imap), from a machine at home which I might call a "server"; I used to log in over ssh, start emacs -f gnus, and go on from there. With the new daemonized emacs, I only need to start emacs once, and can connect to it later, whether that's from my office workstation, or my laptop at some arbitrary location (assuming that I have Internet access, anyway), or even someone else's Mobile Internet Device.
I found one problem with this new modus operandi, though; once I'd logged out of the shell session that started the emacs daemon, accessing remote files with tramp (over ssh) became more painful, as the ssh credential forwarding provided by the ssh-agent responsible for that session was no longer available. The solution I found was to run an ssh-agent instance within the emacs daemon at startup; I have lightly adapted some code by Will Glozer; with my version, a simple
(when (daemonp) (ssh-agent "ssh-agent -d"))in my ~/.emacs does the job very nicely.