I recently encountered Microsoft's Family.show. In case you may not have heard about it, It is a sample Windows Presentation Framework application created by Vertigo. The software became popular and people asked for more improvements for it, so now it has become an open source project on CodePlex.com (Microsoft's Open Source Project Site).
Here is a sample tree of Windsor family. The software has limited functionality, but it has a great UI. I would really love if some decent programmers join the project and enhance its capabilities.
One thing I would like it to have is ability to save file on the web (So it should essentially become a software running on a web page). If that happens, it would be great.
From here I found another free service, and I am going to write about it in my next post.