Third monitor on a 2008 iMac I currently have a 20-inch Early 2008 iMac (iMac8,1), with the iMac display and an external LG display. The graphics chip is an ATI Radeon HD 2400, which, as far as I can tell from the specs, only supports two monitors. Short of getting a new computer (which appears as if it would support three monitors), what are my options for getting a third display to work?
You can purchase a USB to DVI adaptor.  There are heaps of them on the market

eg http://www.gefen.com/kvm/dproduct.jsp?prod_id=8863

This will allow you to keep your existing setup and power another monitor from the USB port.

Just make sure that you purchase one that is Mac compatible as a lot of them on th market are not.