Some are "wow, that's a purple leaf," some are stripes, leaf backs, tints that can manifest in certain amounts of light. Mostly just genus names since they either have several possibilities, or 'the' purple one is obvious.
Begonia, various, mainly Rex'es
Gibasis geniculata Tahitian bridal veil
Gynura purple velvet
Hemigraphis waffle plant
Oxalis purple shamrock
Perilla often mistaken for Coleus
Strobilanthes dyerianus Persian shield
Tradescantia pallida formerly called Setcreasea pallida
Tradescantia spathacea formerly called Rhoeo spathacea
Tradescantia zebrina wandering Jew
What's missing? Show a pic or few if you feel like it!
Tradescantia zebrina on right, T. pallida on left.
LOVE the spots on this Begonia on the left.
Hemigraphis (more purple in person than this pic for some reason.)
Strobilanthes dyerianus, Persian shield, with Coleus.