Tripstir allows you to share future trips. All you have to do is put in your future plans and you'll see who will also be in that city. You can share and discover city wide travel recommendations with a trusted network of friends and followers. It's like checkin on Swarm...in the future.
Instead of posting a status on Facebook or twitter asking for recommendations for your upcoming trip, it automates that. It also has great single user value with guides for travel destinations created by users.
This app was created by my classmate at Columbia Business School. The network you make as an MBA is global. Tripstir allows you to tap into that network to track travel plans and recommendations.
Horizon
Mizzen and Main