By far I like Clarifying Detox Mask by Boscia, I had horrible acne marks after suffering major breakouts..I used pretty much everything.. but what work best was Whitening Mask by Mario Badescu.. is a must try. After that I incorporate Boscia mask and its pretty good combo.
I've heard anecdotal evidence that products with Vitamin E help to fade them. The Body Shop is supposed to have some ones. Also, Neutrogena has an acne mark fading mask - although I think it is for more recent acne than scars, you might want to give it a whirl.