Streaming music- I love this idea but the 3g stuff would be getting in way over my head. Possibly down the line if this thing is successful and I have the $$$ to do it. The goal is to make the perfect running mp3 player so if streaming music makes it perfect, I want to eventually have it. I know being able to listen to pandora on a really long run would be nice.
Walkman- I really like the design but you still have to reach up there to control it. The point of my design being on the side of your finger is you don't have to reach, the buttons are already where your thumb is. And like I said earlier, it allows me to use armswing to match song speed to exercise pace. I think that tempo match feature is going to be really cool but I know it's hard to picture without trying it.
Ipod shuffle- This is my favorite too but I think the wire and the clip are better suited for lifting weights than for all the bouncing of running. And you still have the same issue as the walkman where you have to reach to control it, unless you just hold it the entire time. I like it, but I think I can do better.
Sansa clip- Similar problems to the shuffle.
Buttons you can feel- I totally agree about this because I've done the running with the shuffle inside my sleeve thing. Operating by muscle memory is all you need for running. I don't think screens are necessary for this purpose. It's just one more thing to look at that you don't need and it sucks battery life out like crazy.
Radio- I will def put one in. I could never understand why so many mp3 players didn't have one. Always that was annoying to not include the most obvious thing.
Thanks for the input guys. I'll keep checking back on this thread if anyone has other ideas or questions.