I have recently come across a very small and nice wine store with wein vom fass like they say here in Berlin, but that means that they have the wine on draft. You can bring your own bottle or buy an empty one from them, and then you choose your wine and fill your bottle.
I absolutely love this idea. We went there a couple of days ago for the first time, so we bought two bottles from them, one for white and one for red so for the next time we will just bring them with us :)
They where really nice there at the store and gave us a try of the wines so we could make a decision of which wine we loved the most, it definitely wasn't easy because they had many that where really good, but that just means we have to come there again very soon :)