I widened the front half of the west bed last weekend and decided on ajuga reptans "black scallop". It's probably the darkest form of ajuga, I though the colour would be a nice contrast to the black stems on the colocasia, and the flowers are a nice bonus. They're just little now but they'll spread a fair bit.
Not that you can see them, but here's the bed with the ajuga in.
I though long and hard about what to put between the ajuga, if anything. I finally decided on more plectranthus "mona lavender" after being given an unexpected opportunity to try to strike some cuttings. Yet another limb snapped off (dang that plant is brittle) but this time I thought I'd try to make some new plants from it. I've got a whole set of cuttings going now! On the right is Kenilworth ivy, on the left are cuttings from my tequila blue salvia, and after this photo I added some from the plectranthrus. So far none of them have died and the salvia's already sprouting new growth.
In any case, the pletranthrus should look lovely with its dark green foliage and the purple-black undersides. I still haven't seen it flower yet but it's meant to be beautiful.