It may be useful :
The online compact dice roll you may use on any smartphone (I used it for more than 40 session GMed) : http://www.jaj22.org.uk/wfrp/diceroller_compact.html
Quite the same, non compact, to use on a computer : http://www.gmtools.excelocms.com/dice_roller.html
An excellent iPhone app discovered recently so you don't have to be online at all (0,75 euros - less than 2 coffees on the machine at work) : http://www.thecastle.com/wfrpdice.html
And still the Official FFG dice roller I consider not very useful because it simulates dices but don't give you the final result. Moreover, as I said when it was published, it is not enough simple and fast to use for a GM.