I searched the archives on marrow - and found references to putting large bones (e.g. femurs, other leg and arm bones, ribs even) into either pressure cookers or crock-pots, but from their it gets a bit fuzzy: do you just crack the bones open and scrape them out, or does much of the marrow and such leach out of the bones into the stock? From some of the posts I saw, it looks like you can actually munch down the bones too eh? Any 'easy' ways to get marrow? Do any online vendors sell it?
For organ meat, I live in Houston, and I would think being as red-meat friendly as this town is I could find organs - but I have canvassed the meat markets (don't take that out of context!) and tried most of the big retailers around here, and none of them carry hearts, tongue, or offal in general (well, other than frozen livers in the frozen food section). I tried Whole Foods (pretty much only place I can find grass fed animal products here), Kroger, HEB, Randalls - any suggestions? Though I do have to tip my hat to the Whole Foods butcher guys downtown - they gave me 3 lbs of grass fed suet for $1 - there were just going to throw it away!