Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
Enveloupe - Send snail mail in three clicks.
Triip.me - The happiest way to travel in 227 countries
Felt for iPhone - Handwritten cards for the modern world
HeyLets - The recommendation engine that lets people to see the hot local spots in their city.
Letterly - Send handwritten cards to family and friends