I planted marigolds in my raised beds among my peppers, okra, tomatoes and onions this year and had outstanding results. All summer long I was seeing lacewings (and eggs), hoverflies and ladybugs on my plants. I didn't see ONE aphid all year outside. This was quite a surprise, since my seedlings and OWs and I fought a serious battle with them in the house all winter and spring.
This is a link I just found while looking to see what kinds of beneficial insects marigolds might attract. I'll definitely use it when planning the garden for the upcoming season. Good luck!
http://www.farmerfred.com/plants_that_attract_benefi.html