I've planned half a dozen kitchen sink brews but never had the courage to go through with any of them. Part of the problem is that I'll use an ingredient twice and expect to bring it into regular rotation, so I buy a kilo or two from the online brewshops and figure I'll have it on hand long-term that way, then use a grand total of 100g in the next year. The result is that a kitchen sink brew with two kilograms of weird caramel and roasted malts for 20 liters of beer would just leave me in the position to do another similar kitchen sink brew (or two) before I really cleaned out my rarely-used grains.
The closest I came was a barleywine that I considered hitting with a bunch of carabohemian, Special W, rye, and a few various lighter caramalts. In addition to the same problem of only cleaning out half of the overstock, beersmith had the SRM in the low 30's and I was afraid the final product was going to be a muddled mess. I ended up going the opposite route - 98% 2-row and a handful of oats for a little extra mouthfeel with a five hour boil and some maillardizing wort reduction in a pot on the side. I'll tell you whether or not it was the right decision in another seven months or so...