Not yet. I think an outline should go in the OP once we figure out what's going in the handbook, and a link to the full handbook itself.Is there a single post that has a running list of house rules?
I think Thorgor's post is important. A handbook designed to make an Arbitrator's job easier and improve his/her campaign would ideally include two major sections: Frequently Asked Questions and House Rules. There's another thread w/ a FAQ, and of course GW's eventual FAQ will be the most important, so I'm not sure how to work that into the Handbook. But I'm convinced that a Handbook without an FAQ will be a three-legged horse. At a minimum, it needs links to GW's FAQ and the community's FAQ (if it survives GW's effort).
The House Rule part of the handbook will be much easier to build, though I think the question of appropriate inclusion should be carefully weighed. I don't think we should include any and every idea someone comes up with, since many of them are bound to be bad (my alternate toxin idea, for example, completely forgot about armor saves ), and we want this to make an Arbitrator's job easier, not give them another huge tome to have to wade through.
As such, while it is definitely not appropriate for me to say what should/shouldn't be included, I personally think the best bang for our buck early on will come from first pursuing what Thorgor described as #3: House rules to address major parts of the new game that are unlikely to get any better when GW releases their FAQ.
For example, I think putting in some kind of house rule modifying the "Founding a New Gang" rules to allow access to the Trading Post before the first game is a virtual must. The rule itself is clear and probably won't be changed in FAQs or subsequent Gang War supplements, but it's pretty obviously messed up when people are talking about throwing their first game with naked gangers so they can go to the TP afterwards and get the weapons they want.
Similarly, while I think it likely that GW's FAQ will address some of the questions around Specialists, I personally think that if GW doesn't limit special weapons to Specialists, we definitely need to provide a House Rule that does. Relatedly, the way basic Gangers are treated in general as far as advancements go I personally think really weird and arbitrary (who is GW to say that I can't be attached to my Gangers and make them "stars" of my gang?) and yet another good prospect for a House Rule.
I also agree with @Benoksen that a great place to start is by looking through the NCE and finding the parts that many like better. We know that veteran players of NCE are going to be seriously tempted to do that anyway, so we can provide the service of a standardized method and definition.