I’m always on the lookout for interesting open source projects coming from the Force.com community – there’s some cool code out there, and it’s good to share it. Here’s a trio of projects I’ve recently encountered; they’re all ‘under construction’, so do your due diligence if you’re planning to drop them into a production system, but there are some great opportunities here to get involved and make a contribution of your own.

• ApexBox, by Daniel Hoechst, provides an Apex Code wrapper for the Box API. There’s working code there for some of the File & Folder and Collaboration operations, but as Daniel says, it’s pretty embryonic and could use some work.
• apexcalendar, by Sean Devine, comprises a Visualforce custom component and supporting classes that implement a calendar view of a dataset. Right now, you can show integer data on the calendar, but there are plenty of possibilities for extending this. Sean mentions adding other data types, varying the highlight color based on the data, and showing multiple months, but I’m sure there are many other enhancements folks will come up with.
• Force.com Apex Koans, by Paul Battisson, is a little bit different. In this context, a koan is a set of failing tests in a given programming language. Your task, as the student, is to run the tests, see them fail, edit the code to make the tests pass, then take a moment and reflect upon the test to discover what it is teaching you. There are koans for Lists, Sets and Maps. Work your way through them, reflect on the wisdom therein, and try your hand at writing your own koan.