[databass]

Ternary (or even higher n-ary) storage is already widely used: multi-level cell (MLC) SSDs store more than one bit per cell by using multiple voltages (most commonly 4, i.e. 2 bits per cell). I believe Ethernet also uses 3 voltage levels.

[darkmighty]

Communication systems in general routinely have up to 1024 modulation symbols (32 voltage levels for both the sin and cos carrier).

http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation...