Basil attracts butterflies and repels other pests. Oregano repels aphids. Carrots attract insects beneficial to the garden particularly the tomato. (See more Carrot Companions) Onions/Chives repel pests.
Do your tomato plants grow huge and out of control each year? Do they flop over, get taken over by disease or overwhelm parts of your garden? Do you want bigger tomatoes earlier in the season? If you answered yes to any of these questions then pruning your tomatoes should be on your garden task list this season.