[ZenoArrow]

There are tons of ways to innovate with smartphones, but the technology to do so is either too young, too niche or hasn't made it beyond the drawing board.

To pick three innovative features that have made it into real smartphones, you can look at the Samsung Galaxy Beam pico projector, Jolla's 'The Other Half', and the YotaPhone E-Ink backscreen. Some would argue that these are gimmicks, but isn't all innovation a little gimmicky before it reaches mass market adoption (I'd argue camera phones were in this category originally, and they certainly aren't gimmicks anymore).

Jolla's The Other Half is especially interesting, as it allows for people to personalise the functionality of their phone (along with the look). Whether it takes off or not remains to be seen.

[seunosewa]

Shatter-proof screens would be more revolutionary.

[ZenoArrow]

Not really. Screens on most high end smartphones are already toughened, you'd just end up with an evolutionary improvement rather than a revolutionary one. Plus, there's no such thing as shatter-proof, so the screens should be easily replaceable as well.