There are external video cards which have come out in the last two months.
These are primarily for multi-monitor use for laptops. Basically usb2.0 interface to multiple monitors.
one that has been around for some time is the sidecar pcmia card - http://www.digitaltigers.com/sidecar.shtml
check it out.
btw If you really want something for ur pc..no matter how uncommon...u can find it, u just have to know where to look.