Nope. You want a neutral density
filter -- what it does is reduce the amount of light coming into the lens without adding any artifacts or distorting the image/colors in any way. For the specifics behind the concept, check out the Wikipedia
What you want to be able to do is take a good, long exposure without overexposing the film (or the CCD imager in your digital camera). You might want to pick up a handful of them, actually -- as different ND filters can be used in different situations. You also might consider a couple of graduated neutral density filters to allow you to properly expose ground objects without washing out
the sky/clouds in landscape photographs. I've been pretty happy with the Tiffen filters I've used in the past -- you can expect decent quality from them.