Re: is the Sydney funnel web spider the most poisonous spider in the world

This is certainly a debatable question, as arachnologists often disagree.  
In a recent debate on the Arachno-l news group most seem to be leaning 
toward the South American Ctenid Spider, Phoneutria fera (Ctenidae), with 
the Sidney Funnelweb Tarantula (not to be confused with our funnelweb 
spiders in the family Agelenidae), Atrax robustus (Dipluridae) second.   
Spiders in the genus Sicarius (Sicariidae) are also in the running, but as 
few people ever come into contact with these odd spiders from the South 
American deserts they have not acquired the notoriety that the others have. 
The black widows and violin spiders are further back in the list, with 
other species of Atrax and Phoneutria probably ahead of them.  Keep in mind 
that the ranking is to some extent arbitrary, as we are comparing 
neurotoxic and necrotic venoms and also that a very potent venom may be 
delivered in small amounts, while a less potent venom may be delivered in 
massive quantities.

References:

Australian Insect and Spider Bites: http://www.usyd.edu.au/su/anaes/spiders.html

Unfortunately, there are few good references on P. fera.