Vanilla Extract Barrel - 1 Liter (read the prepping instructions first...don't want to have ejuice leaking all over the floor).
^^^This guy, right here. Drop some vanilla beans in, add some almonds, a little coconut, let it steep for three weeks, filter it through a micron filter, add WTA and give Five Pawns's Castle Long Reserve a run for their money.
...or you could just do Beatle Juice as a trial run. Either way, if you start barrel aging juices, I will be beyond ecstatic!
Edit: I've thought about doing it myself, but I don't have the scratch to buy a liter of Beatle Juice.
As for how I've been doing, They've been working the hell out of us. The money's nice, but I can't remember the last time I had a two day weekend, or a week without at least 10 hours of overtime.
http://oakbarrelsltd.com/1-liter-oak-barrel-with-black-steel-hoops.html This barrel would probably work too. You could use larger barrels, but the steep time would need to increase proportionate to size.