Sixteenth birthday present?

My best friend of 6 (almost 7) years is going to be turning 16 later on in September. I've been trying to think of something both memorable and meaningful to give to her for her birthday. Last year for her 15th birthday, I made her a collage of tons of pictures throughout the years of her with her friends and family and put it in a frame to hang in her room. So I want to do something sentimental like that again, but it has to be even better this time...it's her sweet sixteen! I've decided to throw her a surprise party at my house with a lot of close friends we have from summer camp that we usually only get to see just one week out of the year, and I'm going to invite a couple of her other close friends. But I need to get her a great gift...something irreplaceable. Any ideas?