I've got the Zalman NC3500 which is one giant fan, fit's a 17" but only just, would be slightly larger than a 15". Because it's just the one fan it's pretty quiet which is why I bought it. Lowers temps by 2-3 degrees.
I have the same question! I've searched the Internet for a good one, but they each have many cons, for example, most are 2 years old (I think). I'm still unsure between the U3 Cooler Master (three fans but height is not adjustable) and other cooling stands. There is bound to be someone on these forums that has experience of them, as I am so undecided because all I see is mixed reviews.