Maggs Rare Books  
   Multi-speciality rare and antiquarian booksellers.
   http://www.maggs.com/

Michael Ginsberg Books  
   Western Americana, American History, Canadiana, Voyages and Travel, Bibliography and Reference books.
   http://www.ginsbook.com/

Mickey's Books  
   Rare and hard to find books; specializing in literature, children's, and heritage books.
   http://www.mickeysbooks.com/

Mystical Unicorn  
   On-line shopping for used books, bibliographies and author information.
   http://www.myunicorn.com/

Motte And Bailey Booksellers  
   Specializes in history and science fiction works, variety of general stock as well.
   http://members.aol.com/mottebks/

Mackus Company  
   Acquisition and sale of illuminated manuscripts and historical legal documents. Statement of authenticity included.
   http://www.mackusco.com/

Molly's Bookstore  
   Out-Of-Print, Rare, and used books.
   http://mollysbookstore.homestead.com/mollysbookstore2.html

Meetinghouse Books  
   Old, used and out-of-print bookshop; includes world history, literature, cultural studies, arts, and natural history.
   http://www.meetinghousebooks.com/

MemoraDelia  
   Used science fiction, fantasy and horror books. Plus collectibles, independent press.
   http://www.memoradelia.com/

Mumfordbooks  
   Secondhand rare and old books; first editions, out-of-print.
   http://www.mumfordbooks.co.uk/

Madden Books  
   Rare, used antique and out of print books, specializing in politics and history including Chinese, Cuban, Soviet and Socialist publications.
   http://www.maddenbooks.com/

M. Hofferber Books  
   Specializing in nature, science, how-to, guidebooks, cookbooks and western Americana.
   http://www.webcom.com/outbooks/

ModernRare  
   Rare, out-of-print, and signed books for collectors, specializing in modern first editions, photography, and one-of-a-kind books.
   http://www.modernrare.com/index.cfm

Mockingbird Books  
   Used bookstore with used, rare, out-of-print, and hard-to-find books in all subject areas.
   http://pw2.netcom.com/~mkbird/

MojoMax Books  
   Rare used books; including classical literature, art, history, Americana, and modern first editions.
   http://www.mojomax.com/index.php

Min's Book Cellar  
   Gently used books, including homeschooling, childrens, parents, families, christian, fiction and nonfiction.
   http://www.homestead.com/minsbookcellar/

Mitzi Witch's Used Books  
   Fiction and non-fiction in a variety of areas.
   http://usedbooks.freehosting.net/

Michael Treloar Antiquarian Booksellers  
   Particular enthusiasms are modern first editions, cricket ephemera, and North Australiana.
   http://www.treloars.com/

Maremagnum Librorum  
   Antique, old and out of print books; in English, French, German,Italian and Spanish.
   http://www.maremagnum.com/

Maxwell's Bookmark  
   Rare and out of print books, including California, Scottish history, genealogy, illustrated books.
   http://www.maxwellsbookmark.com/

Mr. Kolk Raamatuantikvariaat  
   Rare and old books from Estonia. Maps, postcards and prints also available.
   http://www.antikvariaat.ee

Moe's Books  
   Catalogs of out-of-print, new, and antiquarian books in all subject areas updated weekly.
   http://www.moesbooks.com/

Moza's Inventory  
   Used books including fiction, mystery, romance, self-help, non-fiction and childrens section.
   http://pages.ivillage.com/mozafamily/index.html