I added my votes too. I need to be able to explain to clients why I put something here rather than there or where professional copy will be necessary or where I need feedback or have questions ... so many notes I need to make that are difficult to cover in an email.

I've been using Notable on top of a PNG of my mockups which is just ridiculously useless.

That said, I do resort to AxureRP when necessary because of the heightened complexity and ability to handle annotations and interactivity. I'd like *not* to have to do so ... and annotations would be a huge step toward making my life easier :)