Envoy - Visitor registration that's changing how guests are greeted in companies around the world.
Cronofy - Unified Calendar API for developers
The Receptionist - The Receptionost is a visitor managemnt solution that has visitor logging system to track visitor traffic.
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.
TractionGuest - Safe, secure workplace for all.
Calendarix - Calendarix is a powerful and easy to use web-based calendar that runs on PHP and MySQL.