I was going to mention watches! I love my Casio Tough Solar and wore it daily for five years. It never reported a charge level less than 'High'. If it didn't say on the box that it was solar, the only thing I would have noticed is that the battery never seemed to run down.

The solar charging is probably the biggest feature I'm missing in my smartwatch, but at least it has a (low-power, daylight-readable, always-on) transflective screen.