Product Customization

[stickygrafix]

Is there a script or plugin or addon that would allow my customers to view a product (say a mousepad), customize it (add text, change font and color, add picture) and get an updated price? I need this to happen "live" so the customer sees exactly what they are wanting before adding it to the cart. I've seen this on other stores but can't figure out how it is done. Flash, Java, PHP, I have no clue but hope someone here can help me.