University of Arizona Master Gardener's Manual
Kelly recommended all the UofA Manuals in her Gardening Virgins class, and they have an awesome Maricopa county calendar. This one is strictly vegetables, so if you're wanting to plant some herbs or fruits intermixed, you'll have to check out some other resources.
The AZ Master Gardener Vegetable Planting Guide is another resource Kelly cited in her class, so give that one a looksie as well.
The Urban Farm Planting Calendar
This is a great resource that I refer to daily- it's great to have when you are perusing around the nursery and want to buy every single gorgeous looking plant you see. The entire Urban Farm website is pretty stuffed with good information for us Desert Urban Farmers!
Gardening in Arizona Blog
This blog is great because it tells you the specific tasks to take on each month for vegetables, fruit, flowers and herbs. If you are looking for more rounded information- this guide is the way to go! The blog is purely informational- there's not a ton of photos or print out lists, but there's a lot of information so make sure to check it out!
Those are my favorites- what resources do you use when it comes time to dig in the dirt?