I participated in my first Yahoo Hack Day yesterday and today. Coding was from noon on Thursday to 1pm on Friday, with hack submissions closing at that time. Basically the idea is what cool Yahoo thing can you write in 24 hours, be it something useful, something fun, or just something you've always wanted to do. The demos started at around 1:20 on Friday, and ended at 4:30, just in time for pizza and beer. While I can't talk about anything publicly since it's Yahoo internal stuff, mine had something to do with how long employees have been at the company. I didn't win anything of course, but I was not only impressed that I got something finished, but it looked decent, and I got a large round of applause when presenting (and several laughs as well), and it's something I can cross off my "must do" list. I've never participated in anything like this before because my coding skills...well...haven't been up to snuff, but as this was all web based (my code was Perl, PHP, MySQL, and an AJAXified (is that a word?) UI) I was able to hold my own without any problems.
6/21 - I found the NBC 11 video of the Hack Day story they did on their website. Unfortunately it's in Windows Media player format (asx actually), and my Intel MacBook Pro wouldn't play it, my parents couldn't play it, and few of my friends could, so I moved it over to YouTube for easy access.