It's a small app to track the last time you did something. This could be anything of your choosing. Some examples include the last time you took a vitamin or updated your resume.
I originally started this as a learning exercise using Prism. I figured it would be a more interesting lesson if I implemented something half-way useful.
The inspiration for the app came from the ItzBeen baby reminder, which you can Google yourself. I don't have kids, but even so I thought the device would be immensely useful, particularly to forgetful people like myself.
Since starting it, I've worked on creating a Windows Phone 7 and WPF (sans Prism) version. These are still a learning exercise in MVVM and modularity. I've purposely tried to divide the parts to be re-usable across both platforms.
Since this is supposed to aid in my own learning, I thought I would make it public for others to see. I don't claim to be an expert or anything, but this does work and it's a good example of how to share code across very different platforms.
As you may already know, while WP7 utilizes .NET it is a specific flavor, and so there are significant differences in the UI and implementation that cannot be shared. But a surprising amount of logic can be shared, and the beauty of the MVVM pattern is that it easily allows this sharing of code.