The printer project is the most original. But this micro controller has so many features and internal components that I an't imagine how many solutions it can fit. Also thinking to the Cypress creator development strategy.
Not a PSoC6 project, but something that demonstrates the PSoC capabilities: my analog-digital mixed scope (I think it like 7 or 8 years old by now). Its a single chip (just the PSoC5 demo board) scope, with 2 analog and 8 digital channels, sampled at 1MHz, with complete triggering and a graphical LCD. Most of the functionality is done in hardware and would not be possible otherwise (e.g. the triggering).