If there's one thing that the Arduino platform is great for - it's electronic artwork. The abillity to control motors, interact with sensors and be programmed without much experience really opens it up to all sorts of uses, and one fantastic example is the "Duck Machine" by David Cranmer. The machine is the result of being commissioned to make something to catch the attention of passers-by at a trade show, and David was successful.
His sculpture consists of forty-nine rubber ducks who are individually-controlled by several Arduino boards, motor shields and can be moved about for all sorts of effects, as shown in the following video:
Due to the sheer volume of motors controlled, a main Arduino sends the required commands for each duck to one of two Mega boards, that each control a share of the motors for the ducks. It's an interesting exercise in high-volume Arduino motor control and art. You can learn more about it, and examine the Arduino sketches for the control system from David's website. And for more. we're on twitter and Google+ - so follow us for news and product updates as well.
If you're looking for an Arduino-compatible board with plenty of I/O to drive many buttons, motors, ducks and more - consider the Freetronics EtherMega:
Quite simply the EtherMega is the fully-loaded Arduino-compatible board on the market today. Apart from being completely Arduino Mega2560-compatible, it includes full Ethernet interface, a microSD card socket, full USB interface, optional Power-over-Ethernet support and still has a circuit prototyping area with extra I2C interface pins. So if your project is breaking the limits, upgrade to the EtherMega today.