Augmented Reality UI could be interesting for HUD and spatial UI elements.
Artist Keiichi Matsuda Blends Augmented Reality With Real-World Scenarios For Kickstarter Video Series
This concept by Mac Funamizu of Japan would act as a scanner, a digital camera, and an internet-connected wireless device all in one package.
Augmented reality, the future of multimedia experience - Affinity VR
Other, more ambitious concepts for digital Heads Up Displays (HUD)