Track one or multiple authors' blog posting frequency and email-notifies these authors if they haven't posted within a set timeframe.
A little background story...
I designed this WordPress plugin for a company I worked for, Carma Systems, Inc. (http://www.carmasys.com/). We have an internal company blog to keep our different teams in touch with eachother, and up to date on the work we do. It is important to everyone at the company to keep the blog updated, but it is easy to forget about it when everyone is busy! That's how Blog Update Reminder was born... the internal blog has many authors, and each author has different requirements for how often they should post, if at all. The system works, because blog authors are sent an email daily (or any specified frequency) until a blog post is made (it's kind of like, the plugin won't stop annoying you until you do what you're supposed to do!). Everyone enjoys the plugin, because authors are happy that they won't forget about making a post, and our internal blog readers benefit from staying up to date with the latest company news.
I feel that my plugin can work as a solution for many types of blogs. An individual may have a commitment to regularly make posts on his/her personal blog, or a company/group may have several people that need to make posts but some people may need to post more frequently than others. All in all, this plugin can keep a blog from dying, which happens too often (unfortunately) in the real world.
This is my first WordPress plugin, and I had a lot of fun developing it! I hope other people will find it useful too. I appreciate any feedback (such as additional features and bugs), feel free to email me at email@example.com. Thanks and enjoy! :-)