VeinViewer

A tip from Medgadget, here's an excerpt from the Lumitex website:

The VeinViewer™ Imaging System utilizes near infrared light and patented technologies to illuminate subcutaneous vasculature by imaging their location on the surface of the skin. Hailed by TIME Magazine as one of the year's "Coolest Inventions," VeinViewer™ is a mobile biomedical device consisting of the following four components:

Infrared light source - The light source emits a harmless, near-infrared light reflected back to the surface from the tissue surrounding the vein, while no light is reflected back from the blood inside the vessel.

Digital video camera - The digital video camera captures the near-infrared light reflected back from the patient.

Image processing unit - The microprocessor adds contrast and projects this image back on the skin in their actual location.

Digital image projector - Using Texas Instruments Digital Light Processing™ technology, the projector displays these real-time images of the vasculature onto the surface of the skin.