Thanks for Asking questions.
Here is something you could do: copy the barcamp unconference model.
http://barcamp.org/
How it works is the "un-organizers" just pick out the time and place (place should be a venue that has at least 2 rooms). And gets sponsors for the event.
Everything else that happens at the actual event is not scheduled.
Say the time to meet is at 9. So everyone starts showing up at around 9 and can have breakfast and mingle. At 9.30, everyone is seated and one-by-one they can introduce themselves.
After the introduction, people who want to give a presentation/speech can register at the front of the room. You write down their topic on a white board and announce it to the room.
Everyone who wants to speak gets 30 minutes to speak. But here is the thing: 2 speakers go together in 2 separate rooms.
And everyone follows the rule of 2 feet. If a presentation is an ad pitch or plain boring, people can leave and go to the other room.
This barcamp format goes very well with computering topics. But its slowly spreading to other industries too.
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Besides this, like the Money Game posts by Dien, you could organize an auction too. And auction a few things at the end of the event for some money.
http://www.ankeshkothari.com/TheMoneyGame.pdf