Pour some Adolfs meat tenderizer on a piece of wet gause and wrap it around the wound for 12 hours. The meat tenderizer neutralizes the enzyme in the venom.
I have also heard that a nitro glycerin patch applied directly to the bite site reduces tissue damage by as much as 95%.
http://www.highway60.com/mark/BRS/bite.asp?Msg=679
Take a backwater carp, slather it with Grey Poupon, vinegar and bat guano, then firmly tie it to the wound with a leather belt. It won’t cure anything, but it will keep other spiders away.