Jeri Ellsworth is the former Valve electrical engineer responsible for the mind-bending awesomeness that is this Commedore 64/bBass guitar hybrid (watch her play it at around 2:15 in the video).
Her latest offering is CastAR, a light-weight augmented reality headset that can also be transformed into a virtual reality headset. CastAR is still in development and is the first offering of a startup called 'Technical Illusions' that partners Ellsworth with veteran game programmer Rick Johnson.
The best thing about CastAR? It's first real application is with board gaming as demonstrated in this video taken at last week's CES trade show in Las Vegas. A few more glimpses of this can be seen in this promo video used with CastAR's recent and abundantly successful kickstarter campaign. Check out the fantastic D&D example at around 3:15.