A couple of weeks ago me and my friends Jeena and Sam Braumeister (Sam Brewing master) have been brewing ourselves.
While we had a lot of fun during the brewing process
we encountered some problems when we were trying to reactivate the yeast. I bought a brewing set a year ago and since the package was broken (there was a small hole in it) the yeast was simply plain dead. Since we've been brewing on Saturdays it was simply impossible to get a new pack of beer yeast. We also didn't wanted to wait until Monday + x days for the yeast to arrive because we feared spontaneous fermentation.
Thus we bought a flask of Maisels Weisse and a flask of Erdinger Urweisse and tried to reactivate the yeast of them.
Surprisingly the yeast in the Maisels Weisse beer began to grow after we filled it into some warm water and fed it with sugar. Thus we added it into the brewing bucket and after four weeks we got, respecting the fact that this was our first brewing attempt, a decent beer.
And even more cool: I wrote Maisels an email telling them this story. I wasn't expecting much, didn't even think that they'd answer my email. But after a few days I got a nice answer, saying that they like it that I began home brewing and that they're proud that this was possible. Cool!