Miss the ed editor?  Never tried it?  Too confusing?
I just picked up a modern book on the subject:
Ed Masteryby
Michael W LucasGot my inner Ken (and Dennis) on after reading this book.
So yeah, ed isn't for everybody.  But if you dig cat redirections, herefiles and so forth, this is a nice step up before going to either vi/nano/emacs etc.
The author has his own sense of, um, humor.  Definitely needed for a book on ed. 

I suppose I should make the request that ed be one of the built in apps for TC's busybox for us cli lovers.
Makes a great holiday gift for the whole family!  Well, maybe one of us weird ones...