It may seem strange to be heading into spring and summer and discussing wet tolerant plants, but we seem to have had about three weeks of pretty solid rain. Finding plants that will tolerate and even thrive in such habitats can often be challenging. There are some well know wet tolerant plants such as kahikatea, pukatea, swamp flax and toetoe, but these are all big and not always a good choice for small urban gardens. Many of the native grasses (Carex, Juncus, Macharina) do very well in wet conditions and come in a range of sizes and colours to meet most requirements. Astelia species (A. chatamica, A. grandis) both perform well in wet conditions. If you are after flowering plants Kanuka and Manuka are wonderful. Manuka in particular comes in a range of flower and leaf colours and sizes from ground covers to large shrubs.
If you are looking for a plant that is smaller in size, will tolerate wet feet, exposed conditions and will provide birds with fleshy berries; species of Mahoe (Melicytus) could be useful. Some Melicytus species become small trees whilst others (M. crassifolius, M. alpinus, M. obovatus) remain 
tightly branched shrubs.