- MercenaryAuthor: Mack Reynolds, Lloyd BirminghamReleased on Project Gutenberg: January 20, 2008
- Mercy Philbrick's ChoiceAuthor: Helen Hunt JacksonReleased on Project Gutenberg: December 1, 2003
- Merely Mary AnnAuthor: Israel ZangwillReleased on Project Gutenberg: December 10, 2006
- Merry Words for Merry ChildrenAuthor: Hoatson, A.Released on Project Gutenberg: May 27, 2008
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- Messages from the Epistle to the HebrewsAuthor: H. C. G. (Handley Carr Glyn) MouleReleased on Project Gutenberg: August 4, 2007
- Messages to America: Selected Letters and Cablegrams Addressed to the Bahá'í's of North America 1932–1946Author: Effendi ShoghiReleased on Project Gutenberg: September 17, 2006
- Messages to CanadaAuthor: Effendi ShoghiReleased on Project Gutenberg: September 17, 2006
- Messages to the Bahá'í World: 1950–1957Author: Effendi ShoghiReleased on Project Gutenberg: September 17, 2006
- Messenger No. 48Author: James OtisReleased on Project Gutenberg: November 26, 2007
- Messer Marco PoloAuthor: Donn ByrneReleased on Project Gutenberg: February 1, 2000
- MetamorphosisAuthor: Franz Kafka, Wyllie, David (Translator) [Translator]Released on Project Gutenberg: August 17, 2005
- Metlakahtla and the North Pacific Mission of the Church Missionary SocietyAuthor: Eugene StockReleased on Project Gutenberg: November 1, 2004
- Mexico: Its Ancient and Modern Civilisation, History, Political Conditions, Topography, Natural Resources, Industries and General DevelopmentAuthor: C. Reginald (Charles Reginald) Enock, Martin A. S. (Martin Andrew Sharp) HumeReleased on Project Gutenberg: April 2, 2007
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- Mezzerow Loves CompanyAuthor: F. L. (Floyd L.) WallaceReleased on Project Gutenberg: August 14, 2007
- Micah Clarke: His Statement as made to his three grandchildren Joseph, Gervas and Reuben During the Hard Winter of 1734Author: Arthur Conan DoyleReleased on Project Gutenberg: December 1, 2005
- MichaelAuthor: E. F. (Edward Frederic) BensonReleased on Project Gutenberg: May 14, 2006
- Michael Angelo Buonarroti: With Translations Of The Life Of The Master By His Scholar, Ascanio Condivi, And Three Dialogues From The Portugese By Francisco d'OllandaAuthor: Charles Holroyd, Condivi, Ascanio, Francisco de HollandaReleased on Project Gutenberg: September 19, 2006
- Michael McGrath, PostmasterAuthor: Ralph ConnorReleased on Project Gutenberg: September 12, 2006
- Michael O'HalloranAuthor: Gene Stratton-PorterReleased on Project Gutenberg: December 1, 2005
- Michael Penguyne; Or, Fisher Life on the Cornish CoastAuthor: William Henry Giles KingstonReleased on Project Gutenberg: October 25, 2007
- Michael Strogoff; Or, The Courier of the CzarAuthor: Jules VerneReleased on Project Gutenberg: August 1, 1999
- Michael's CragAuthor: Grant AllenReleased on Project Gutenberg: June 1, 2004
- Michael, Brother of JerryAuthor: Jack LondonReleased on Project Gutenberg: May 1, 1999
- Michel and Angele [A Ladder of Swords] — CompleteAuthor: Gilbert ParkerReleased on Project Gutenberg: November 18, 2004
- Michel and Angele [A Ladder of Swords] — Volume 1Author: Gilbert ParkerReleased on Project Gutenberg: August 1, 2004
- Michel and Angele [A Ladder of Swords] — Volume 2Author: Gilbert ParkerReleased on Project Gutenberg: August 1, 2004
- Michel and Angele [A Ladder of Swords] — Volume 3Author: Gilbert ParkerReleased on Project Gutenberg: August 1, 2004
- Michelangelo: A Collection of Fifteen Pictures and a Portrait of the Master, with Introduction and InterpretationAuthor: Estelle M. (Estelle May) HurllReleased on Project Gutenberg: December 3, 2005
- Michelangelo's ShoulderAuthor: Wetterau, John MoncureReleased on Project Gutenberg: February 1, 2004
- Micrographia: Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries ThereuponAuthor: Robert HookeReleased on Project Gutenberg: March 29, 2005
- MiddlemarchAuthor: George EliotReleased on Project Gutenberg: July 1, 1994
- Middy and EnsignAuthor: George Manville Fenn, Rowlandson, G. D. [Illustrator]Released on Project Gutenberg: May 8, 2007
- MidnightAuthor: Octavus Roy CohenReleased on Project Gutenberg: February 1, 2004
- Midnight In Beauchamp Row: 1895Author: Anna Katharine GreenReleased on Project Gutenberg: September 29, 2007
- MikeAuthor: P. G. (Pelham Grenville) WodehouseReleased on Project Gutenberg: February 1, 2005
- Mike and PsmithAuthor: P. G. (Pelham Grenville) WodehouseReleased on Project Gutenberg: January 1, 2004
- Mike Flannery On Duty and OffAuthor: Ellis Parker Butler, G. C. (Gustavus C.) WidneyReleased on Project Gutenberg: March 9, 2005
- Mike Fletcher: A NovelAuthor: George MooreReleased on Project Gutenberg: September 21, 2005
- Mike Marble: His Crotchets and Oddities.Author: Francis C. (Francis Channing) WoodworthReleased on Project Gutenberg: March 29, 2008
- Mildred's Inheritance; Just Her Way; Ann's Own WayAuthor: Annie F. (Annie Fellows) Johnston, Diantha W. HorneReleased on Project Gutenberg: November 22, 2005
- Miles Wallingford: Sequel to "Afloat and Ashore"Author: James Fenimore CooperReleased on Project Gutenberg: February 1, 2004
- Military Instructors ManualAuthor: J. P. (James Perry) Cole, Oliver SchoonmakerReleased on Project Gutenberg: January 9, 2005
- Military Memoirs of Capt. George CarletonAuthor: Defoe, DanielReleased on Project Gutenberg: December 23, 2004
- Military Reminiscences of the Civil War, Volume 1: April 1861-November 1863Author: Jacob D. (Jacob Dolson) CoxReleased on Project Gutenberg: November 1, 2004
- Military Reminiscences of the Civil War, Volume 2: November 1863-June 1865Author: Jacob D. (Jacob Dolson) CoxReleased on Project Gutenberg: November 1, 2004
- Milk for You and MeAuthor: Randell, WinifredReleased on Project Gutenberg: May 21, 2008
- MillenniumAuthor: Everett B. ColeReleased on Project Gutenberg: March 8, 2008
- Milly and OllyAuthor: Ward, Humphry, Mrs., Ruth Mary HallockReleased on Project Gutenberg: August 31, 2004
- Milly DarrellAuthor: M. E. (Mary Elizabeth) BraddonReleased on Project Gutenberg: February 19, 2006
- MiltonAuthor: Mark PattisonReleased on Project Gutenberg: August 1, 2005
- MiltonAuthor: Raleigh, Walter Alexander, SirReleased on Project Gutenberg: June 4, 2007
- MiltonAuthor: John Cann BaileyReleased on Project Gutenberg: August 9, 2007
- Milton's ComusAuthor: John Milton, William BellReleased on Project Gutenberg: November 15, 2006
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- Mind and Motion and MonismAuthor: George John RomanesReleased on Project Gutenberg: August 9, 2007
- Mingo, and Other Sketches in Black and WhiteAuthor: Joel Chandler HarrisReleased on Project Gutenberg: October 28, 2006
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- Ministry of DisturbanceAuthor: H. Beam Piper, H. R. Van DongenReleased on Project Gutenberg: February 24, 2007