Add 2 additional displays to an iMac?

[wicky]

I've got a 24" iMac with a second monitor connected via the DVI port.

I'd like to connect a Wacom Cintiq 12WX and wondered if there is any way to add this without disconnecting the second monitor?

I know there's only one DVI port, but wondered if a device exists that can be added to allow the tablet to be connected too?

Thanks