Stack Exchange, the network of community-driven Q&A sites, held a developer contest recently for their API. Developers were invited to write applications that work with Stack Overflow, Server Fault, Super User and Meta Stack Overflow. Among the winners were an iPhone application, a printable view and a web widget.
Co-founder Jeff Atwood announced the winners for the contest, which saw 85 applications and 24 libraries submitted. Apart from the Top 3 applications, special prizes were also given to developers, who submitted the most applications/libraries to the contest. That is a very encouraging sign and something that others can emulate.
Contests continue to be a popular way to generate interest in a platform, but it also helps providers find out what they're doing right and wrong, as Atwood wrote in the announcement post:
Your feedback helped us drive the API forward and make it better for everyone--but most importantly, you built amazing apps and libraries!
Interestingly, all entries were stored in public and voted by members, similar to Stack Overflow answers, as you can see in the complete list.