There might be motherboards there with 8 individual fan plugs, and maybe someone else can point you to one.
There are 2 different options though.
There are case fan splitters:
http://www.newegg.com/Product/ProductList.aspx?Description=fan%20splitter&Submit=ENE
Or there are case fan controllers, where you have a box (which you can usually put in one of the 5.25' front slots of your PC which is powered by a . . . (wait, this must've moved on from molex, right?) molex/sata.
First option you need a motherboard with 4 fan plug connections (you don't want to split it twice, they do require a certain power to run)
Second option you're pretty much independant of motherboard.
And you can combine the two, if you wish. a 4 dan controller with splitters.