Ryan,
The reason you struggled is the same reason that all of us struggled. We had Tomlinson, Hall, and Smith give us very vague definitions of what differentiated instruction is and how to implement it. This is why all of my principals can not put it in layman's terms. They still like to say the word, though.
In regards to your sites:
1. Really Books. I am going to look into this. This could be a great history or government resource. I could have my students create great "products".
2. Polly Everywhere. I hope that it is as easy as you say it is, because I am going to use it, next year. I will create surveys to assess the learning styles of my students.
3. Adobe. It would be a little too creative for my class's needs. It would create too much creativity and not enough learning. The forest would be lost for all the trees.