In the management screen in the Mifi, there is a WWAN status, which has a listing of how much data used. This is not exactly what shows on your account, but it's pretty close.
FYI, for reference, if you are streaming Pandora from your iPod touch, is uses about 30MB/hr.
I've noticed for typical laptop use, it uses about 50MB/hr.
you can install an iphone application called "mifi" to your ipod touch and it will track how much time you used each session (and it will tell you how much charge the battery has left), but to see how much time you've used the last 10 or 30 day top up period, you have to log in to your account. You can do it from the ipod touch using safari. Either go to the virginmobile web based control panel, or you can just log in at their regular web site using the "phone number" of your mifi and the password to gain access to your broadband2go account.