Another Open Hack has come and gone, leaving more than 300 exhausted developers, 400 pizza boxes, 1200+ donuts, and nearly 500 cans of Red Bull in its wake. We’ve hosted a few of these before, so we had some idea of what to expect, but the great thing about Hack Day is you never know what’s going to happen (including executives getting down on stage to Girl Talk).

We were blown away by amazing ideas and hacks. After 24-hours of working through the night on new creations, our hacker guests demoed more than 45 hacks to our panel of judges –- internal: David Filo (Chief Yahoo!), Ash Patel (EVP, Audience Products Division), Cheryl Ainoa (VP, Media Engineering); and external: Matt Mullenweg (Automattic/WordPress), Om Malik (GigaOm), Rashmi Sinha (SlideShare) and Jeff Clavier (SoftTech VC).

We saw some comedy, some shtick, and some basic crowd appeal, but the overall winner was truly a hack that will enhance a user’s experience on Yahoo!, taking advantage of the sneak preview of the Open Mail Development Platform that was in effect for the weekend. A few developers from Xoopit created a Yahoo! Mail application that enables users to more easily share multimedia within their inboxes.

Prizes were also awarded in other categories, including some that were invented on the spot by impressed judges. These ranged from Best Technical Hack (officially called “Filo’s Technical Merit”) to Best User Experience to Most Prolific to the Bleeding Purple Award, which went to the team that used an incredible number of Yahoo! services to power their hack. Om even created the GigaOm award – an invitation to the upcoming Mobilize conference – given to the creators of “Where are My Drivers?”, an application for small business owners to track location and communicate with their delivery vehicles. The full list of winners can be found here.

It was a blast to meet hackers from around the world and talk tech, get creative and code until our eyelids drooped. We had developers join us not just from Silicon Valley, but from Brazil, Canada, England, India, Israel, Korea, Spain, and Taiwan as well. Three hackers even won a contest to come from Malaysia, the Philippines and Singapore to show their stuff.

And that’s just a taste of the buzz out there. If you’ve got time to kill, search for #hackday on Twitter or “openhack08” on Flickr – you’ll find a bonanza of more than 2000 photos and 400 tweets. Here’s a sampling of what people were twittering:

• #hackday was excellent.
• #hackday was awesome!!
• Had an awesome time at #hackday. Ate, danced, drank, met and talked to some awesomely smart people. Girl talk ROCKED.
• Totally enjoyed the reunion aspect of #hackday.
• This #hackday is off da hook.
• My cup runneth over of yahoo technologies #hackday.

The next Open Hack kicks off in Taiwan later this week – stay tuned to developer.yahoo.com for an Open Hack coming to a city or country near you!

Chris Yeh
Head of the Yahoo! Developer Network