Ah, the dreaded overlaps.
Non-megalithic culture/structures in prehistory(e.g. Iron Age forts, souterrains, brochs I guess). 'Romano-British' to 'Dark Age' (probably stopping at the time the English kingdoms became fully formed). Proto- to early Mediaeval (i.e. from coming out of the 'Dark Ages' until the Normans stopped being foreigners and started on England and Wales, which would cover perhaps barrows to mottes and stop short of castles proper). Neglected or obscure site-types generally.
Let's say two new camps basically. 1) That which TMA feels outside its remit and a time period to the withdrawl (sic) of the legions. 2) Early Christian to early Norman Conquest.
Just suggestions.

The big issue for me is "continuum". Prehistory doesn't cease because literate Romans took over a part of Britain and wrote something down which we regard as "history" The ever so temporary Roman occupation was an interval during the ongoing Iron Age. What exactly do we mean by "megaliths" - big stones? What is the consensus view of the purpose of standing stones - waymarkers, boundary posts, memorials? Didn't they evolve into Pictish slabs and Christian crosses? Aren't they megaliths also?

I believe that the cut off point is just too early and much of interest is lost and so slips in through the back door eg Romano-British settlements often called "Celtic" villages, medieval mottes justified because there might be an earlier barrow inside, these odd currick cairns of which I know nothing but what I have read on TMA - are they not medieval or modern? Contributors are clearly pushing against the restraints and something has got to give sooner or later.

Ok. I'm definitely doing something for this. First steps are underway.

You will be very glad to know that I only really intend to set it up and host it. I am not particularly interested in editing and moderating it, but will be taking some interest (as I love Romanesque!)

If there's any volunteers who'd like to put some hours in when it's running then mail me:

tomfourwinds @ tomfourwinds.com (leave them spaces out natch!)

It will basically be a similar system to all the other sites of this ilk - drill down to site and post or view.

Let's see if it works. If it crashes and burns then so be it. If it does then I have a great URL to use for something else :-)

[Oh. And it will be commercial to pay for the space and the bandwidth.]