I like my learning projects to also be useful. If not to me then to somebody around me.
What are some good projects I could code using WCF (to learn it) that I will be able to put to use for myself, or for someone or some organization I may know?
What I am not interested in tutorials, or books on how to learn it.
Hate to say it, but I used to do the "kill two birds with one stone". You'll find that it's too hard to do. You'll spend countless hours learning the technology and making a lot of mistakes/lessons learned. You may end up with a useful app...but it wont be as "pretty" as you'd like it to be and you'll end up wishing you could rewrite it. Especially if you are trying to learn WCF, there is so much to the technology....either way.....here is an app:
I did a WCF chat application. I created a web version (thin client) and a WPF version (thick client). By doing the chat application:
-----Thin Client web app
teaches you how WCF works with ajax
teaches you how to use the BasicHttpBinding
teaches you how to host WCF in IIS
teaches you about how WCF will scale given multiple users
teaches you "pull" architectures
-----Thick Client Winforms/WPF app
teaches you how WCF works in a thick client (duh)
teaches you how to use a Duplex binding
teaches you how to host you WCF app in either a windows service, console app, or IIS7
gives you insight on security/firewall requirements when dealing with thick clients
teaches you "push" architectures
gives you insight on thread safety when dealing with OneWay calls
-----How to make it useful
It would be great if there was a "plug-able" chat application out there that I could put on my websites. You can provide it as a service to other developers.
-----Books (even though you don't want it)