The AppNite demo presentation that drew the biggest collective "ah's" and head nods at O'Reilly's ETech was Underlying's Dipity, described as a Wikipedia for timelines -- a way to organize the Web using time. Many companies are experimenting with timeline concepts, including Google, because it's a new way to give information more context. In the case of Dipity, timelines become a way to bring communities together.Like many of the companies demonstrating on stage last night, Dipity is brand new, launching just over two months ago with a team of ex-Yahoo employees bent on creating something new. The idea is to use all of the data available (in this case from your Facebook profile) to create an actual timeline which can then be used to create connections with your community. Here you can see things like who has attended (or will attend) the same events, the same schools, the same groups.

Dipity presumes the existence of data, of course, and while its first platform, Facebook, offers plenty of it, to be truly useful its users must constantly flood the system with data, most especially time-related data. Luckily, it can add anything with an RSS feed, including Twitter and Flickr, so it starts with a pretty solid foundation of data. CEO Derek Dukes (I know, he sounds like a character out of Boogie Nights) said that Dipity has harvested data to create 30,000 pre-populated timelines, which will give early users some interesting things to correlate a personal timeline with.

Once the timeline is built, your friends can work collaboratively on that timeline with you. It's also sharable not only with your friends but in broader contexts. For instance, Dipity has taken advantage of Facebook's public pages so you don't even have to be a Facebook user, you can Digg your timeline, or even post it in a blog. If you're not into Twitter, then you can do mobile posting using SMS.

Putting aside the fun you can have discovering surprises about your connections to people and events, there are some great potential business benefits. Dukes said that one of the original Dipity ideas was to look at data from Salesforce or SugarCRM, giving people the ability to search for and correlate data around certain incidents and time frames.