The New York Times had an article last Sunday on how personal recommendation services are becoming more popular – driven by the belief that the best advice comes from people you know and those in your digital and personal networks as opposed to a service such as Yahoo Answers.

For anyone using Twitter or Facebook, the power and effectiveness of tapping into your networks is clear. To me, one of Twitter’s “killer apps” is being able to use the collective knowledge of the crowd.

Yesterday, I went to a start-up event in Montreal featuring three travel sites – Travellr, Viajeros and YowTrip.

One thing that struck me during their presentations is how travel is such a personal experience, and how the best travel experiences don’t come from guidebooks but, instead, the people you meet along the way that suggest places you’d never otherwise have discovered.

This makes recommendation services such as Twitter a natural way for people to get travel advice from an extensive network of people who have real insight into what to see, do and hear, and a willingness to share it.

The question is how online travel services can effectively integrate Twitter into their offerings as opposed to having it exist as a standalone. Traveller, for example, has a way to ask questions that can be published on Twitter but there’s current no way to integrate the replies from Twitter users into Travellr’s database so Traveller users can benefit from what people are saying on Twitter.

My sense is the tighter integration of Twitter into online services will be a powerful and effective way to enhance the information available while extending the overall community. In some respects, Facebook is working on it with Facebook Connect but the reality is we’re just scratching the surface.