I had marigolds planted about every 2-3 feet apart all around my garden last year, and the hornworms still feasted on my tomatoes!
Yesterday, I was googling stuff to help deter the "bad bugs" and came across this:
http://www.sparkpeople.com/resource/...es.asp?id=1324
http://www.gardeningknowhow.com/prob...ith-plants.htm
http://lifehacker.com/5583176/draft-...arsh-chemicals
Headed out now to see if I can find some dill, mint, yarrow and a few others to see if they will help any with the tomato monsters.... wish me luck!!