The Buddhist Trinity
OK, so I know there are four statues in this picture, but the one at the front shouldn't be there! It is (I Think) a statue of Ksitigarbha (Dia Tang Vuong) that someone has seen fit to include on this small shrine outside the ancestor hall at Kwan Yin Temple, Canley Vale.
The Pure Land Buddhist trinity is made up of Amitabha Buddha (at the centre), Mahāsthāmaprāpta at the viewer's left and Kwan Yin at your right. The trinity is filled with all kinds of symbolic importance, which I just can't recall at the moment. All I know is that Kwan Yin is inextricably linked with Amitabha (she carries an image of him in her headpiece), and that Mahāsthāmaprāpta (try saying that after a few bears) appears almost nowhere else in Buddhist imagery - she is one of the great mysteries of Buddhist worship. She just pops up in this particular trinity and that seems to be her only job.
This is an extremely popular trinity in Buddhist worship, but there are some others that spring to mind and that regularly appear as the main objects of worship in Buddhist temples - Sakyamuni, Kwan Yin and Ksitigarbha; Sakyamuni, Samantabhadra and Manjusri; and Sakyamuni with his two key disciples, Ananda and Mahakasyapa.