Basecamp offers project management tools to collaborate and communicate. The Basecamp PHP library created by Netvlies contains authorization with OAuth, API calls, and identification. It aims to facilitate project management with assigned projects, to-do lists, and active projects.
Our API directory now includes 42 collaboration APIs. The newest is the Devot:ee Upload API. The most popular, in terms of mashups, is the Box.net API. We list 77 Box.net mashups. Below you'll find some more stats from the directory, including the entire list of collaboration APIs.