I think the winner will have to be a permanent, purposeful tank with at least one fish. So far the betta ina 29g has it! Anyone else? I'll sweeten the award a little. In addition to the live mosquito larvae I'll throw in some slightly chewed water lettuce and the ghost shrimp of your choice.
I just wanted to throw my tank in there, but I live in New York. I really can't come to pick anything up. However, it is very amusing that I have the most understocked tank.
Maybe not a winner, but surely close...
I've got a 10g that's only home to two 1/4" ramshorn snails ATM. It's my QT/plant growout tank, pretty much empty and waiting for any new or sick fish who need a cycled tank (I keep it cycled by feeding it fish food).