There's a group called "Handbook Editor." I'm told this allows a member to modify other peoples' posts in the handbook subforum, allowing shared authorship after a fashion. As far as I know, the group has zero members right now.
I remember when the group was first discussed, many people were adamantly opposed to the idea of allowing their handbooks to be modified by others. That's probably doesn't bode well for your idea either.
Huh.
You see, I'm the opposite. I'd actually like to encourage people to modify my handbooks.
Take the Wizard Guidebook I'm working on.
So I'm reviewing my work on the spell handbook only to find a number of errors I've let go unfinished. So I've been spending the past week just fixing the Spell Lists. (Going through the final spellcheck now. I believe there are 3345 official WotC spells.) I never did get back to reviewing the spells themselves, which means the spell handbook has a whole bunch of work to be done with it.
Then I come across
The Platinum Spell Collection Now there's a cut and paste I need to get around to.
You see, I know people like to post things on line, but I don't always have internet access. An off line resource is a far better choice for me and I have no doubt there are a wide number of people out there who would feel the same way.
Frankly, I don't care who gets credit as long as the information itself is correct and complete.
I guess my point is, I wouldn't mind getting help to speed this thing up. I was rather hoping someone out there had already worked out a Handbook Creating Group or something. I'd be happy to found it myself, but it's difficult to gage interest.