Sac spider

http://goafrica.about.com/od/africanwildlife/tp/Africas-Scariest-Spiders.htm

Sac spiders are thought to bite more humans than any other spider. Their venom contains a cytotoxin, which means it kills cells and will lead to tissue breakdown and blistering at the bite site. Sac spiders are quite pale, the most common house species are pale greenish, tan or straw colored. They have distinctive long front legs that face forward and wave about when on the hunt. Sac spiders actively hunt at night and weave together a protective tube of silk to rest in during the day. Sac spiders are very useful to farmers because they control pests. There are many species of Sac spider in Africa, at least 3 species have been identified in Egyptian cotton fields alone.