Uhm...
I assume you are talking about case fans? Or do you mean heatsink fans? Are you talking about posative or negative pressure? I also assume this post has a point other than to sound pornographic... Your post is more than a little vague. Perhaps some clarification? Throw us a bone here...
Assuming the the post is, in fact, about case fans, I suspect the answer is both. Since intake fans should suck air into your case and exhaust fans should blow air out. Hence the terms "intake" and "exhaust". If you are talking about the HSF I think many/most perform best with the fan blowing air onto the heatsink. Though there are a couple that perform better in the opposite configuration. If there is some point here, perhaps you can enlighten us and we can better help with your specific situation.
\Dan