As I was composing this list, I had the strong feeling that I'm leaving out something really obvious, but I couldn't figure out what. It's possible that my brain is trying to insist that flowers are leaves. It does that sometimes.
In any case, if you think of any other houseplants that aren't somewhere in this post, let me know in the comments and I'll add it.
Cryptanthus 'Elaine' and other Cryptanthus cvv.
Dracaena marginata 'Colorama.' (Madagascar dragon tree)
Ficus elastica 'Tineke.' (rubber plant, rubber tree) (new growth)
Hoya carnosa 'Krimson Queen' and other cvv. (wax flower) (leaf edges or centers)
Hypoestes phyllostachya (polka dot plant) (species and some cvv.)
Pedilanthus tithymaloides, variegated (devil's backbone) (with temperature fluctuations)
Peperomia griseoargentea cv. (some cvv.)
Stromanthe sanguinea 'Triostar.'
Syngonium podophyllum 'Neon.' (arrowhead vine)
I'm pretty fond of Hoya carnosa (though the 'Krimson Queen' in the picture is getting a little cranky lately: I think I made it wait too long for water), and I like Pedilanthus tithymaloides so well that it feels borderline unfair to even mention it. Cryptanthus spp. are also very nice plants, though I'm a little pissed at the genus at the moment, because one I bought from the consignment store this summer turned out to have mealybugs (I checked it, though! I swear I checked!), and they spread to (at least) one of my other plants before I found out and threw them away. Still, aside from that, they've always been good plants for me, and are pretty easy.
Aglaonema cvv. (a few relatively uncommon varieties)
Aloe striata (coral aloe) (leaf edges, in very bright light)
Alternanthera ficoidea 'Partytime' (large portions of leaves)
Ananas comosus (ornamental pineapple) (some cvv.)
Begonia rex-cultorum and some other Begonia cvv. (some cvv.)
Breynia disticha (=Breynia nivosa) 'Roseo-Picta' (snowbush, snow-on-the-mountain)
Caladium cvv. (some cvv.)
Echeveria cvv. (some cvv.)
Episcia cvv. (flame violet) (some cvv.)
Fittonia albivenis (nerve plant) (some cvv.)
Neoregelia cvv. (some cvv.)
Peperomia clusiifolia 'Rainbow' (leaf edges, in bright light)
Philodendron 'Pink Princess'
Saintpaulia ionantha cvv. (African violet) (some variegated cvv.)
Solenostemon scutellarioides 'Pink Chaos,' some other cvv. (coleus)
Tradescantia fluminensis (wandering Jew) (some cvv.)
variegated Tradescantia spathacea (oyster plant, Moses in the cradle)