Tree trunk spiders belong to the Family Hersiliidae. There are about 150 species in this family and many more undiscovered. I found one the afternoon we arrived at Sukau Bed & Breakfast Lodge at one of the trees behind the lodging house.
They range in size from about 10 mm (0.4 inch) to 18 mm (0.7 inch)long including the "Tails"
Photo above : Tree spiders are beautiful with multicolor pattern that helps them in camouflaging against the tree trunks they live on.
Being very well camouflaged for life on the varicolored trunks of trees, they have an interesting way of capturing prey. Rather than making a web that captures prey directly, they lay a light coating of threads over an area of tree bark and wait hidden in plain sight for an insect to stray onto that patch. Once that occurs, they direct their spinnerets toward their prey and circle it all the while casting silk on it. When the hapless insect has been thoroughly immobilized they can bite it through its new shroud.
They can watch your every move, but you cannot see the spider with only your 2 eyes.
More about Tree Trunk Spiders : http://en.wikipedia.org/wiki/Tree_trunk_spider