Emacs lisp is just so immensely sticky... once you cross the initial "what's up with this crappy lisp?" threshold, and have a finger caught in its web, you suddenly just want to put your hands all in. And then find more hands to add to the pot.
I expect it to stay around a good, decent while :)
It's such a nice UI paradigm married to a decent lisp (any lisp is better than no lisp :)). Once you get the actual hang of it you can't ever leave it. Just like real coffee vs. instant abominations.
Any recommendations for a good starter guide? I've done some lisp here and there, a bit of Clojure, and some other FP-style things (e.g. Elixir). I'm not scared by parens :). I'm just not sure where to start with elisp and getting into a good groove with it.
Edit: also a long-term Emacs convert, just haven't written any of the elisp myself.
I myself have discovered everything I know along the way, and have read no guides, so unfortunately don't know any of them. Tho C-h t is the unavoidable initiation to emacs the editor.
Using tools lik Org mode, Rmail, Elfeed etc. gives you many opportunities to write some useful elisp, which is a pedagogical experience.
Emacs is like the mildly beautiful geeky girl which you fall in love with: whenever she spots you inclined to some new cute girl, instead of going mad with you, reveals such a wonderful piece of her interior world that you just forget the other one :)
Also, m4. I use it together with awk and bmake for a couple websites. I plan to port awk scripts to sth. else though, I keep forgetting awk.