Well, since our original idea didn't work quite as well as we thought, I've brainstormed a few others thanks to people in the apartment below me who know nothing of the 12 o'clock rule. We could still use dungeons as recruiting tools, but say so right out that it is a recruitment run so we can get to know each other and help new people learn the ropes, and that it will NOT be a speed run that most established players are looking for. I've also thought about possibly using Anet's forums, since I believe they have one specially for guild recruitment, but I'll need to look into that. As a side note, it might be kinda fun to make a little music video/slide show with all the screen shots we've accumulated to post it to the website (with our classic witty commentary, of course), then add that to any recruitment message we spam.
As Ben mentioned before, the biggest influx of new and returning players may not happen until around launch, but we can still have fun with it.
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"I am a cipher. A cipher wrapped in an enigma, smothered in secret sauce."