A guy and I at work have a design that would make a modular 1 gallon keg assembly. It would fit five 1-gal kegs in roughly the same space as a 5 gallon corny. The idea would be that you could fill a gallon keg from your gallon carboy, enjoy your ~12 beers without needing to bottle. Once finished, you could remove the one you filled, quickly disassemble and wash it and keep the other 4 in place (assuming they are full.) The connections would be the same as a corny (one liquid line, one gas line per keg [working on a shared gas line as well]). Do you think anyone would be interested in these? I don't know how many brewers make 1 gallon kegs for testing out new recipes and such, so I don't know what kind of market is out there for this. The entire assembly would actually be stainless steel.