Given the space, cover crops are an easy way to improve your soil structure without a lot of hand labor. You can cover crop anything from a few rows or raised beds in your yard, all the way up to cover-cropping large swaths of land. Generally cover crops are planted during the winter months, when your garden will be less active, however, you can cover crop areas during the summer as well that need additional revitalization.
Some benefits of cover crops can be increased organic matter, better water retention, better drainage, and an increase in plant available nitrogen.
For more information on the benefits of cover crops and what kinds to plant:
See the information from the National Gardening Association
Or a helpful chart from the Gardening Resources at Cornell University