Usbhub

The usb hub gotta be externally powered, prolly by a 12V source.

micro usb hub 4 port not self powered : http://uk.gizmodo.com/2006/07/31/lindys_micro_usb_hub.html
brando's usb hub http://usb.brando.com.hk/prod_detail.php?prod_id=00022

abix 13 ports http://www.abix.fr/hub-usb-20-13-ports-alim-externe,article,021150.html#

brando reader + hub 3 ports http://usb.brando.com.hk/prod_detail.php?prod_id=00531&dept_id=015&cat_id=039

super slim 7 ports : http://store.worldstart.com/product.php?productid=3943

small 7 ports : http://www.cdiscount.com/search/hub+usb/informatique/wifi-reseau-bluetooth-cpl-nas/advance-hub-usb-20-7-ports/f-107152402-HUB007U.html?search=hub+usb