Have you considered inpatients (spelling)? I grow them here in zone 7, but have also seen them thrive in Hawaii. In fact, there they grow along the roadside.

SG

There are so many, but probably the most common and easiest to acquire are impatiens, the more common ones and New Guinea impatiens. New Guinea's can even tolerate more sun once your shady conditions change. Also, don't forget colorful foliage annuals. Coleus now comes in such an abundant variety of colors, patterns and leaf shapes. I especially love the newer larger leaf coleus. My favorite is "Limelight" which literally glows in the dark! Caladiums are great, beautiful, large-leafed foliage plants, but if you've underground munching critters, they'll go after the tubers. You'd want to start them in pots and just plunge the entire pot in the ground then. Another favorite of mine are torenas or some people call them "Clown or Monkey Flower". I'll plant these really close together in a variety of colors to creat a nice splash.
Good luck!

Linda