Cronofy - Unified Calendar API for developers
Travel Diaries - Create your own travel diary to capture your experiences
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.
Magpie - Female travelers club - meet women like you when you travel
ApPHP Calendar - ApPHP Calendar is a PHP calendar script that may be easily integrated and used with various PHP projects, such as schedulers, event, etc.
tripcake - Doodle for travel plans with friends