The ICUITI iWear video glasses connect directly into your Apple iPod video - No extra power pack or external electronics necessary.

These lightweight video glasses are directly powered by the iPod video.

The ICUITI iWear generates a virtual 44" screen viewed at 9 feet distance. The image is generated by two 320x240px (230,000 pixels) LCD Displays.
ICUITI says that the battery life of the iPod video stays the same and powering the video glasses uses the same energy as powering the iPod screen. iWear for iPod only weighs 4 oz. The glasses can also be used for 3D viewing. It switches into that mode automatically when the corresponding video signals are applied.
The ICUITI iWear HMD sells for $299 at the ICUITI web site.

See also the Mikimoto iBeans glasses. Those require an additional external pack.