Begonias, african violets, Streptocarpus spring to mind, at least they
are the ones I have used. with african violets you can take a leaf, put
it in water and in a few weeks it will have rooted, then plant it out.
With the others I have taken a large leaf, made several cuts on the
underside of the main vein and then placed the leaf on compost on a
propogating tray, used sort of staples made from wire to hold the leaf
down against the compost surface, in a few weeks you will have little
plantlets develop, just cut the leaf up and plant them.