What about all the other educational resources?
It is important to keep in mind...
If we don't classify a resource as unique and compelling, it does not mean that it has no place in your classroom.  Our limited amount of time and resources can make investigating all internet educational resources haphazard and ultimately superficial.  By requiring you to focus on a certain set of resources with a specific definition and goal increases the time that you have to probe the projects at depth.  While it may be tempting to want to accumulate resources other than those that are unique and compelling on the continuum, understand that both you and your students will benefit more by focusing on those projects that best address the aforementioned skills as well as take advantage of the Internet as a communication tool.