I have 5.5 Gallons when I transferred my lager to the keg so I put the extra half gallon in a growler and lagered in it but there was no more fermentation to do really and it was a twist on cap that I unscrewed a little bit the first few days.
P.S. Craigslist is great, I just got a gas pressure washer last night from it.
On tap: #79 Berliner Weisse 1.030 9/20/12, Flanders, Barleywine, Wild Blonde (1.045 blonde hopped up and fermented with WLP644), #80B rett Saison
Fermenting: #82 Galaxy IPA, #83 Black IPA
Aging: #67 Bareleywine 1.116 11/07/2012, Flanders 2 batches 1.056 and 1.060 12/12/11 and 3/26/12, Kriek, 1.052 12/11,