When we have these kind of celebrations at my KM website, one of our fans hosted a 24-hour "online party" that consists of a live chatroom and an online radio station that plays DT songs. We've had up to 20 people attend at any one time, but since the DTF community is much much bigger maybe a few dozen or 100+ people might partake. I'm not too knowledgable about about chatrooms and stations, but someone could do that possibly and post the links here.
We could also write a press release or something small advertising the day and we could all post it on our Facebook status, then it would spread like wildfire as people share it. Idk, just tossing out ideas.