In the meantime you could write ones for Infiltration and Monster Factory. You know, if you just wanted to write-up Secret Histories. I think you have some promos out there too without Secret Histories. Entertain us Donald! Entertain us! Games aren't enough; we demand stories!
Well I can do Monster Factory.
FFG would like to control the flow of information on Infiltration, so I may never post a secret history there. I made the prototype in 2003; you were thugs robbing a bubble gum factory (not stealing bubble gum, as some people immediately think it must have been - you were robbing a factory, and factories make something, and this one made bubble gum). You will have something close to the prototype if you play with most of the variants they included - draft items at the start, extract not download, floors mixed.
The Dominion promos are all covered in one place (http://www.boardgamegeek.com/thread/667119/secret-history-do...). I think the Kingdom Builder promos are all covered, just not in one place. They're all expansion outtakes (Caves and Island from the fourth expansion, which at this point I expect in 2016; Capitol from Crossroads). The Gauntlet of Fools promos are in the main secret history for it.