Geography Matters produces an assortment of outline maps in different formats. Some are available in the larger 23" x 34", double-sided format. Their USA map is colored and labeled on one side but has a blank outline on the reverse. .
Single-sided maps 17" x 22" in size are available for Ancient Civilizations, Israel, Europe, Europe and the Middle East, Africa, North America, South America, Australia, and the United States. These are outline maps, printed in black-and-white so children can label and color them. If you get the laminated version, children can erase and reuse them.
Some maps are also available in packaged sets. The Continent Outline Map Set includes a 23" x 34" map of Asia (with Australia and Antarctica), plus 17" x 22" maps of Europe, Africa, North America, and South America. A 16" x 22" U.S. map is thrown in as a bonus. These are all laminated outline maps that can be reused many times.
For maps you can print yourself, see the review of Uncle Josh's Outline Maps on CD-ROM.
Check their website for more information and specific prices.