It is a velvet mite.
Family: Trombidiidae (Velvet Mites)
Species: Trombidium sp.
Mites in this family are easily identified by their bright red coloring and velvety appearance.
Photo taken 24 December 2004, after a day of 46C (my personal record!) followed by massive rains.
Mites (Acari or Acarina) are the most diverse and abundant of all arachnids, but because of their small size (usually less than a millimeter in length) we rarely see them. The ticks are an exception, in that they are usually big enough to see, especially when they are filled with blood. Red velvet mites
are also among the giants of the Acari (to 10 mm), and can often be seen hunting on the ground or on tree trunks. Water mites are rarely more than a few millimeters long, but their bright colours and rapid movement often bring them to our attention. At the smaller end of the mite size range are species like the human follicle mite or the honeybee tracheal mite - small enough to raise a family within a human hair follicle or within a bee's respiratory tube, and too small (ca. 0.1 mm) to see without a microscope.
Mites are also among the oldest of all terrestrial animals, with fossils known from the early Devonian, nearly 400 million years ago (Norton et al. 1988, Kethley et al. 1989)
. Three major lineages are currently recognised: Opilioacariformes, Acariformes and Parasitiformes (Krantz 1978, Johnston 1982, Evans 1992)
. About 45,000 species of mites have been described - a small fraction (perhaps 5%) of the number of species estimated to be alive today.
Nice arachnid link
*edit: photo added.