Marigolds, I heard, kept some bugs out of gardens. Well, there is more to it than that. Garden planting is an art, or rather a mathematical, scientificated equation. To maximize growing space and reduce insect devastation, complimentary planting is a fabulous idea. I'll have to try it next year.
Rosemary: by Carrots
Chives, Garlic: by Roses
Marigolds: near Tomatoes, Strawberries, Squash
Basil repels flies and mosquitoes.
More info: http://toadstoolponds.wordpress.com/2007/12/07/why-plant-marigolds-in-your-vegetable-garden/
I love the scent of marigolds. Throw in some used coffee beans and you may end up with a 5 foot marigold like Melbel.