http://tomatoville.com/showthread.php?t=3
The above list is one Mischka compiled and updated in April of 2013, which I think is worth looking at. I see that some info is still a bit wrong, one seed cp has gone out of business, but on the whole Ithink it's a good guide and also indicates which companies are owned by registered Tville members
That list is in a much longer thread where individual companies have been listed with their own threads and some great comment about some and not so great comments about others, and looking at all those compnies should give you the info you want without folks having to reinvent the world of seed companies in this thread.
Carolyn