Summer Organization Push - To-do/Note Taking?

This summer i want to get way more organized for just my life and my senior year of high school. I have done some research on the GTD system, I’ve read the book, tried programs, etc, and have tried various note-taking methods.

I would like to have my GTD/notes available for me everywhere i go, so online or iPod touch compablity in a must. And a iPhone/iPod touch offline interface is also a major plus. I live on my Mac so it has to be Mac compatible too.

So have any of you had any experience with GTD programs or programs i hear about like Evernote or Toodoole.

Please help me get organized this summer. I want somewhere where i can turn to dump all my thoughts, ideas, and have a running to-do list. Give me your suggestions.