If you have an enthusiast MoBo, you can use the BIOS functions .... the Rampage series for example from Asus can control up to 8 fans and that's w/o doubling any up.
Otherwise, the NZXT Sentry 2 isn't bad....the LX is very problematic. Here's a wide list
http://www.frozencpu.com/cat/l3/g47/c17/s286/list/p1/Fan_Accessories-Fan_Controllers-525_Controllers-Page1.html