Northern & Central Midwest
Xeriscaped is a great site for answering questions and finding information about all aspects of xeriscaping, from water harvesting and storage to plant choices. The plant lists are good, although not grouped by hardiness zone so you will need to do a bit of research. You can access back issues easily, so there is more than enough information to set you on your way to a xeriscaped landscape.
Dry-Land Gardening: A Xeriscaping Guide for Dry-Summer, Cold Winter Climates by Jennifer Bennett (Firefly Books, 2005) is a garden guide that does what other books on the subject don't do -- gear their suggestions to dry Zone 4 and 5 gardens. This book has a master list of flowers, shrubs, trees, and groundcovers that will thrive under the conditions of dry, cold climates. The author also does great service to the reader with tips on water saving and irrigation. It will make you think twice about your landscape in terms of sustainability and stewardship.