The router ports are powered and can be used to recharge a cell phone for instance. If you want to share the USB drive on your home network the simplest way is to attach it one of your computers then follow this : http://www.ehow.com/how_6832635_share-usb-hard-drive.html
Downside is you have to leave the computer on to share it.
The experts here may sugggest NAS as mentioned as an alternative in the linked artice, but for my needs this works out fine and since all my devices have GB NIC's, access is VERY fast.
you can buy a second router with enabled USB ports and set it up as an access point
I'm using just this way a WD router that I got on sale for $30
I'm running my Asus RT-N16 behind the Actiontec exactly in this way, with a 3T HDD plugged in to the USB port. Works fine.
The problem with this arrangement is precisely that it is a USB port, and therefore very slow. An eSata alternative would be a very useful solution. Perhaps adding an eSata card with a separate external HDD to each workstation would be the best of all worlds.
VZ has had a lot of time to address the USB ports on the Actiontec, and so far nothing has happened.