Do the two have to be the same project? Sounds like you saying you have to implement something as a Windows Form application, then again a Web app.
If you can do two apps, or perhaps two apps that work together, I had great fun a while back developing a Windows Form application that spidered the internet for images. When it found one, it downloaded it. All those images where databased and stored on the media server here in the house, and anyone on the network could lauch the intranet homepage (the second application, web portion) and browse and rate the images.
Lots of cool features to learn about from WebClients to Threaded processes (if you choose)..don't know how complex you want to get...