I had an epiphany a couple of days ago, so to speak: instead of just me and chpe writing every Epiphany extension thinkable, why not make extension-writing such an attractive proposition that nobody can resist?
So I wrote a HOWTO. It's already linked from Epiphany's Project Page and hopefully it'll be hosted there in a few days, too :).
Already, at least one person (lwillis) has used it to start off an extension (a Dashboard hint-finder for Epiphany 1.1). He and chpe helped me iron out all the bugs, so it's a perfect HOWTO now!
Epiphany Extensions has moved to GNOME CVS now. Exciting -- that means I have to get a GNOME CVS account! I'm quickly making my way up the ranks to uberhackerdom.