Most newer motherboards have 2 x usb2.0 and one usb3.0 header for front usb ports. There's also more ports in the back of the pc on the motherboard
You could get a front bay device eg http://www.pccasegear.com/index.php?main_page=product_info&products_id=20953&cPath=262
and add more to the front.
Or just http://www.newegg.com/Product/Product.aspx?Item=9SIA1JM0JG9043
and plug into your usb 2.0 and 3.0 headers