I recently stumbled upon a great Kitchen Garden Planning tool that was easy to use, full of helpful tips, and free! At Gardener's Supply Company you can create as many beds as you can imagine in your head. Their Kitchen Garden Planting Map allows you to select from 30 vegetable groups by just clicking the item and dragging it onto a grid. After filling and arranging the bed to your desires, you can then access a completed bed with helpful information on each type of plant. If you read through the hints, you'll know if you want to move anything around or change out various plants. When done, you can print it up or send it to your email account. The Planning tool is based on a 3' x 6' raised bed, but you can ignore squares if your bed is smaller or create two if it is larger and add them together later.
Other helpful items on the site include a Vegetable Encyclopedia and Zone Maps. If you live out west, you'll want to use the Sunset Gardening Zone Maps instead due to the multitude of micro-climates that exist. Just checking out the one on Gardener's Supply has my area in the wrong zone, so I'm sure others in the west are not all that accurate as well.
Under the step-by-step planting guide is a very helpful little calculator for the amount of soil you would need for a raised bed. This soil calculator would be great for anyone wanting to amend a bed with compost or other material as well. Just add the dimensions of the area including depth and click the button. It gives you amounts in bags, cubic feet, and cubic yards (for bulk). I could have used this years ago! My math isn't that great when standing at the nursery with kids asking me questions at the same time!