Some personal notes...when doing business with these companies; you will find that you are communicating DIRECTLY with the owners of these small businesses...since it is their personal reputation on the line; you will find that they go above and beyond to provide great customer service...I have found that to be the case with EVERY one of the companies listed above that I have dealt with. (I have NOT dealt with all, just most.) Several offer items other than tomatoes.
Double Helix is well worth visiting...beautiful photos, and the owner is a biologist; who is designing heirloom tomatoes that will be EXCLUSIVE to his company. He can put you on a list so you can be among the first to receive the offerings of his 'new' tomatoes. Check it out.
Select Plants does NOT offer seeds; plants only. A text-intensive website; but loaded with information, and an AMAZING selection of live plants...shipping is a bit rough, but he has gone to a great deal of trouble to get nice healthy plants right to your door.
Heritage Harvest Seed is another beautiful site, but they are in Canada, so you might want to inquire about seed being shipped to the states. They provide that service, but it seems to take a while. However; they have a wide selection of rare and unusual tomatoes. Fun to check out, even if not ordering.
Marianna's has another stunning selection, but still lists her '2011 Offerings', so I am not sure what is going on there...she might be working on updating for this year.
Tons of offerings to troll through, but you weren't doing anything this holiday (for some) weekend, anyway...right? Enjoy.
Great post! Jam packed with info! Thank you.