Roll-a-Dice 3D is a free android app that lets you roll as many dice as you like.
Tap or shake your device to roll as many dice as you want.
3D graphics and realistic physics with no irritating sound effects.
You can add or remove 6-sided dice using the blue buttons in the bottom left of the screen.
Other dice can be added by typing in how many you want of each into the text box between the two blue buttons.
E.g.
6d6 + 10d4 + 3d8 will add six 6-sided dice, ten 4-sided dice and three 8-sided dice.
Dice currently supported:
d4, d6, d8, d10, d12 and d20