One more comment--would it be possible to change the angle for #31. It's a very cool concept but it's hard to tell that's a one. I thought it was two telephone receivers and my co-worker thought they were ducks.
the letter "O" can act as a standalone icon that can be used on web presentations, powerpoint, even promotional gears such as T's and Coffee mugs..oh yeah coffee mugs. I have done several merchandise mock ups and it look great.
2. the icon will serve well as a app icon for any custom software development if your company does this as well.