I am a market research specialist attempting to assist a new business start-up who has services he would like to sell to hedge fund and automated trading firms. I wish to conduct some survey work and would like to find either (A) email addresses of some of the key firms, or (B) snailmail address for same. Is there a single directory, association or listing of all or most trading firms so that I can find names to conduct such a survey? I have the list from TradersLog.com, so I have a good start... however, I am looking for others as well. It seems that there is a fairly large number of independent firms -- that are transparent -- difficult to find. Any thoughts on how to find a good, representative listing of most of these targets?