Plain text for notes/bookmarks/todo items/wishlists with my own markdown-like syntax for formatting. I use a small app (Editorial) on my iphone and Dropbox to sync.
Thanks. This is probably 1 of my top 3 choices at the moment. It is timeless, no need to worry about service shutdown, and robust and free. Of course, it probably has the most learning curve as I have to type out everything.