Agapanthus are also available in dark blues (Wavy Navy, etc.).

There is also a climber that looks for all the world like an ornamental grape (but isn't related at all). Has green leaves heavily speckled with white, pink stems and develops fantastic blue berries. Altogether a very pretty plant and much better behaved than the ornamental grape. Pity I can't remember it's name!

Wombat: have you remembered the name of that climber yet?? love to know...
Rose

It's Ampelopsis brevideduncelata (you get your money's worth in the name alone). According to Botanica, common names are Turquoise Berry Vine and Porcelain Vine.

The species has a plain green leaf and is obviously a bit a pest. The varigated varieties are less vigorous. 'Elegans' is especially pretty with pink splashes on the leaves.

Other suggestions are (but I don't know how they will go in tropical climate):
Solanum Rantonetii (s. Azureum)- Paraguay Nightshade. A fast growing shrub with long pointed leaves and showy violet blue flowers with yellow centres in profusion over a long period. Likes sun or part shade, grows to 2m. Mine don't like the frost, but are growing new leaves in the spring.
Dampiera Diversifolia - a low growing Australian native groundcover which thrives in most well drained soils. Plants withstand some dryness, but prefer to be kept moist. Partly shaded position is preferred, but will tolerate full sun.
Coryopteris "Heavenly Blue" - small to medium perennial shrub. Masses of true blue flowers in mid summer to autumn. Grow in full sun.

Other suggestions - duranta, felicia amelloides (blue daisy), pansies, violas, petunias, lobellia, Brunfelsia (Yesterday, Today, Tomorrow), blue hydrangea, agapanthus, salvia, veronica.

I will try anything that is even vaguely blue, and the mauves and blues mixed together give an overall blue tone. I just look for anything with blue flowers on the label when I visit the nursery!!

Ann