What do you think about the AAT Accent program?

American Accent Training, by Ann Cook? Well, I don't know about the training on site, but I used her book and CDs. They're the best.

If you want to pick an american accent, or at least get very close to it, I strongly recommend that one. You need to work a lot on this, of course.

If you are referring to Ann Cook's book, then yes, it's good. I think it's the most popular one, not sure you'd find anything much better. That said, it's not "perfect". It's a good starting point if you want to understand American English. I mean, some parts might seem confusing and you might come across some little mistakes, and she will be telling what you have to do, but don't take that book like it's the bible, don't believe everything she says. That book will help you understand how Americans speak, and it'll help you "listen" to American English, so then you can improve by yourself over time. For example, she says that n's after t's are not pronounced in American English, so she says twenty -> twenny, center -> cener, Toronto -> Torono... That's what I do, but don't expect every American to talk that way, I hear 90 as niny (no t), ninety (with t) or ninedy (tapped t), so as you see you'll actually hear a lot of different pronunciations, not only what she says. And by the way, I really believe Ann Cook's got an accent that is not neutral...

So, yeah, go ahead and learn from Ann, it is definitely something you've gotta do if you are serious about learning American English.

Hi Feathers,
yes, she probably say that. You know, I didn't read it all and learned it by heart, I just tried to remember the most important things and see if I recognize some of those featuers in Americans' speech. For example, I didn't try any of those exercises with the rubber band... I still have tons of doubts about the stress in sentences, but I don't think Ann explained it completely. I mean, she spend a lot of time trying to teach where the stress goes, but she doesn't mention where to put the stress in common structures (for example: negative sentences, sentences with particles like only, also, already, etc.)
I hope I'll learn that over time, as soon as possible.