I have been really wanting to use the Visual Studio Online (VSO) service for a while now with Mud Designer. I have been holding back primarily because Mud Designer is open source, while VSO is meant for closed-source team projects. TFS doesn't come with an easy way of maintaining two repositories of the same code-base, while maintaining the version history of the source.
The solution to this was Git, but the Codeplex project was hosted on a TFS instance. I then discovered - (thanks to Richard Banks for answering my Stackoverflow post) - that the Codeplex team could convert my project to a Git repository. I promptly fired them an e-mail and had my project converted.
Now that Mud Designer was sitting in a Git project, I cloned it to VSO. Now any time I push changes to VSO, I can simultaneously push changes to Codeplex. This lets me make use of VSO's Agile work items, such as User Stories, sprints and bug tracking, while keeping the source freely available to the public. Win win!