Inverters, Gates
Multiplexers, Decoders
Frequency dividers, Flip-flops
Analog switches
Tristate or open-drain outputs
Schmitt-triggers with any switching levels
Pull-up's, Pull-down's
Current sources, Current sinks, Current mirrors
Current comparators
Voltage references
Voltage comparators (2mV offset)
Op. amps (2mV offset)
RC oscillators, Quartz oscillators
Switched capacitor circuits
And numerous other analog functions
Very complex digital circuits like microprocessors
Any analog circuit with very high accuracy