GUC2020DW6 USB 2.0 External DVI Video Card
By IOGEAR

The IOGEAR USB 2.0 External DVI Video card instantly adds an additional high resolution DVI display through your USB 2.0 port. Simply install the driver, plug the adapter into the USB 2.0 port and you're ready to go. - Extend your desktop across both displays allowing you to increase your productivity like never before. ... 

SEE2 Xtreme USB 2.0 to DVI External Video Card 1920X1200 Max Resolution
By TRITTON Technologies

Introducing the SEE2 Xtreme, the most versatile USB 2.0 DVI external video card. The SEE2 Xtreme supports PC DVI resolutions up to 1920 x 1200 and VGA resolutions up to 2048 x 1280. The SEE2 Xtreme also supports widescreen resolutions and video playback. The patented technology supports extended desktop, mirroring and primary modes. ... 

Millennium P690 Plus LP PCIe x16 256MB
By Matrox Graphics

Reliable, ultra-low power graphics solution with wide enterprise flexibility. - The low-profile Matrox Millennium P690 Plus LP PCIe x16 offers 256MB of graphics memory, full DualHead support for two digital or analog monitors at high resolution and pristine image quality, and can be upgraded (via a Quad-HD15 cable) to drive four analog monitors. ...