As a part of creating a culture of innovation, we decided to hold a Hack-a-thon within our organization. Hack-a-thons have become really popular as a way to bring like-minded folks together; one of the biggest is from my alma matter. Our definition of Hack-a-thon was a time-box opportunity to create a team of folks and pursue a pet project of your choosing culminating in a short presentation of what you did to everyone focused on working software. It's different from a challenge or long-running competition.

Goal

Decide on the goal ahead of time. Do you want participation? Do you want innovation in a particular area? Our first Hack-a-thon, we wanted to encourage a culture of innovation so simply participation on any level was success for our group. We let people choose projects and technologies liberally (not related to any project we had going on). Subsequent events we held had more constraints (innovating with a particular technology, for example) to help foster usage of that technology.

Before the Event

Publicize the event for the staff to know what's coming. Use posters, emails, flyers on desks. Get the word out that it's happening and create buzz. Maybe even do some goofy stuff like music videos or something to get people talking. Hold events like mixers to get people to meet and talk about ideas leading up to the event itself. Register teams prior to the event (who's on the team and what's the team name) somewhere public like on a wiki page. Get them to volunteer what they're working on (some will use it to recruit, some will refuse and keep it secret, it's all good fodder for the event).

During the Event

Start late in the day (we did Thursday around 4pm) with a kick-off event. Bring food and drinks. Get everyone together and officially "start" the Hack-a-thon. Allow the teams to go all night in the space if they want. Encourage teams to claim working spaces and make it theirs for the duration. Take pictures. Feed people regularly. Stock lots of drinks (alcoholic and caffeinated). Have leadership round the teams to ask questions, offer advice, lend support. I've seen some folks create a formal group of consultants to round and act as advisors. End the next day (we did Friday with presentations). The roaming advisors and leaders also helped people think about practicing their presentation at least once.

Presentations

Set expectations of what people should present. We wanted actual working software and prioritized the demo as the show-and-tell. We were clear that everyone got 5 minutes and had a formal time keeper. We worked to get the audio-visual set up and working well so transition time was minimal. Remote participation is possible but hard; work on getting the video conference and screen sharing nailed if you have remote teams.

Have judges, maybe 3-4 people, who can see the presentations and ask questions. In the end we had the judges confer and agree on awards (see below). The judges can be a great way to create exposure outside your group (we included executives like the general counsel to create excitement that it wasn't just a department event).

Give multiple awards focusing on a number of things you want to recognize. For example, most creative use of a new technology. Best design. Best new solution to an old problem. We would attach famous people (Edison, Branson, Jobs) to help give the award more flair (the "Steve Jobs award for Best Design"). Having multiple ways to recognize teams gives you the ability recognize more people.

Logistics Considerations

Make sure you have space to spread out
Make sure you have adequate bandwidth and Wifi for the people who will participate (and all their devices)
Have a space big enough for the presentations, here you can create a party atmosphere by encouraging folks to sit on the floor and crowd in (folks will be crispy anyway if they stayed up all night)
Get some key folks to act as ring-leaders to help model the behavior you want during the event (we had a guy bring in an air mattress to set the tone that he was sleeping at the office that night)
Run a retrospective on the event to learn what worked for you and what didn't; then do it all over again.