We are coordinating through a Google Group which anyone can sign up for here. I add new people a few times a day.
I've also set up a Hipchat room (no account required) here: https://www.hipchat.com/g5XbLeBKR
I'll be updating the former with information leading up to the event, and was planning on using that plus the HipChat room to coordinate people on the day of the event.
I suspect our chosen strategy might change during the day depending on the giving patterns of the other orgs.
I didn't know about this google group until right now stubling about it. You should probably make it more visible - a "here" is a bit low-key.
As you may know, on May 6, there will be a large one-day price-matching fundraiser for Bay Area Charities.
The relevant details are right here at MIRI's official website.
And this is the webpage to visit to donate.
For those of you who didn't read the two links above, here's the important information.