The goal of a Show and Tell is to bring like-minded people together in person to share their projects, ideas, and knowledge.
Step 1: Set a Date, Set the Schedule, and Advertise
Here's the schedule we've been using
7 - 8 PM : mingle and eat snacks; sign up to present a project
8 - 9:30 : Show and Tell
9:30 - 11 : mingle, finish the snacks
The Squid Labs Light Salon was initially advertised among our personal emails lists and the MIT Club of Northern California's mailing list. Over time we collected enough people to start our own Salon mailing list, and eventually people would hear about the event and ask to be added to that list. This time around we added the notice here on Instructables to the mix.
Step 2: Clean Up and Prepare a Big Room
If you expect more people than can comfortably look at a laptop screen, beg, borrow, or steal a video projector.
If you can, prepare a gong or some other obnoxious way to let presenters know they've started to bore the audience. Yelling "Gong! Gong!" also works.
Optional: Setup a table for people to give away free stuff.
Step 3: Prepare Some Snacks
Step 4: Set Up Something Fun to Keep Kids Entertained
Full disclosure: The balls had already been out and inflated for a week for us to play in. They weren't set out intentionally, we're just incapable of putting our toys away before company comes over. Apparently no one at Squid Labs is above a mental age of 14.
Step 5: Sign Up to Present, and the Theory of the Evening
I'm pretty sure we got the "self-organizing" format of the Show and Tell from O'Reilly's FooCamp. However, considering that only half of the people that show up will have RSVP'ed telling you what they're going to show, and half of the attendees won't sign up to present until the presentations are actually underway, this seems the only logical way to do it.
Also, have people put on name tags, and sign an attendance list with their emails so they'll know about the next one. We've swapped back and forth between signing in on a computer or paper. Paper is a lot easier, but some portion of the handwriting will be illegible.
Step 6: Run Through the Projects; Have Fun
The host should start the presentations by welcoming everyone, describing how the evening will run, and presenting his own project. The host should then run through the list giving everyone a couple of minutes, or until the audience gets bored, or the questions get too technical. Since I have everyone's name and project already on the board, I introduce them to keep things moving briskly. If the presenter I've just introduced has a laptop and doesn't have it connected and ready to go, I move on to the next presenter immediately, and come back to the laptop presentation when it's actually ready. The way you do it will vary by number of people and location.
Watch the audience carefully to ensure they're still engaged. If they aren't, use the gong liberally. If the presenter keeps talking about "quantum mini-golf" use the gong again. When they try to give quantum mini-golf's URL, carefully spelling it out and repeating each letter, keep using the gong until they get the message. Remember, you'll dealing with nerds, and sometime they need some "tough love."
Same deal goes for highly specific and technical questions. The audience members really interested in a project will have time to talk with the presenter one-on-one in the third half of the evening.
PS - http://quantumminigolf.sourceforge.net/
Step 7: Cut Loose
Step 8: Finishing Up
People will want to stick around and help clean up. Let them! You have to get started on all the great project ideas from the evening!