Calvetica is an iPhone application by Mysterious Trousers (who also make Dialvetica). It is a calendar application that aims to provide users with a clean, minimalist interface with very little UI chrome, and provide a fast and functional experience.
John Gruber of Daring Fireball said of the app:
$2.99 calendar app for the iPhone and iPod Touch, with an emphasis on fast, convenient event creation and a very crisp, stylish UI design. Behind the scenes, it’s built on the iOS system level calendaring APIs, so it syncs perfectly with the built-in Calendar app.
There are two themes available, “Patented Calvetica Red” (the light grey theme) and “Black Is The New Fuschia” (pictured below).