Spiders and arachnids make up to 5-10% of all Arthropods in rainforest canopies, represented most famously by the beautiful, bright Greenbottle Blue Tarantula (Chromatophelma cyaneopubescens) (1).
Orb-weaver spiders make up a majority of spiders found in the rainforest and can weave beautiful webs, although members of this group of spiders also include Bolas spiders, also known as fishing spiders, which swing fragments of sticky web at moths and flies to catch their prey.
1.) Floren A, Deeleman-Reinhold C (2005) Diversity of arboreal spiders in primary and disturbed tropical forests. Journal of Arachnology, 33, 323-333.