The works of
Harry Turtledove, and occasionally Laura Frankos, feature many real-world product brand names and incorporate them into the story - e.g., McDonald's, Coca-Cola, Walgreen's, etc. However, they also feature numerous fictional products, particularly in alternate history stories, or works set in the future. While some of these fictional products are crucial to the plot of a given work, most are passing references meant simply to provide momentary background color to a fictional world, often serving as inside jokes.
Throckmorton car, the most luxurious railroad car of the 19th century, presumably an analog of the Pullman car. In " The Scarlet Band," we learn that trains in the United States of Atlantis do not have these, much to James Walton's chagrin. 
Angels City Ethernet Station One News, the program for which Joe Forbes is a reporter. 
Elworthy, Frazer and Waite, the law firm which Samuel Dill belongs to.
General Movers, a flying carpet manufacturer, analogous to General Motors.
Hand-of-Glory Press, an Angels City-based publisher of magecraft technical manuals. Judy Adler is a proofreader and copy editor. 
Lenny's, a restaurant known for pies, apparently an analog of Denny's. 
Ma Bell, a magical telephone company. An analog of the  OTL company Bell, colloquially known as Ma Bell. MasterImp, a credit card company. 
Food and drink:
6+, described by Beckie Royer as a fizz, lemon-limey, on the order of Sprite (an OTL brand which apparently exists in this alternate). The name seems to be a multi-layered reference to the real-world brand 7 Up and Turtledove's own story "  6+" (part of the series) which, in turn, comes from a soft drink in Earthgrip Robert A. Heinlein's novella The Man Who Sold the Moon.
Hupmobile, mentioned in passing. In OTL, a brand bearing this name was discontinued in 1939.
Lancelot, mentioned in passing
Pegasus, mentioned in passing. Vance, described by Justin Monroe as being as popular as Chevrolet in the home timeline.
Workermobile, a U.S.-made vehicle, mentioned in passing. 
Humanoid Systems, Inc. The main character has a job application for a technical editor at this company, whose nature is a complete mystery to him. 
Benjamin and Levi Bank of Portsmouth, Virginia. In " Though the Heavens Fall," Jeremiah Gillen becomes a client in 1805. 
Universal Protective Services, advertised as the best on Saugus. At the end of " The Great Unknown," Professor Jennifer Logan, now an unwilling celebrity, makes a call to this agency. 
Rincian, a brand of wine.
Marco Pollo, a chicken restaurant in Hawthorne, California, Ralph Sandars imagines that it will likely be put out of business by McDonald's.
Naviopedra, a remarkably efficient brand of batteries made in the Brazilian Empire. 
Earth Socks, founded by Mullnor and Agnes.
, a disreputable tabloid newspaper in the The Unvarnished Truth Federacy. When trying to find a soapbox for their whistle-blowing, Jeng Ho Stavros Monemvasios and Andrea Dubois quickly discount this option. 
Manassas, a Confederate brand. In 1914, a Presidential limo of this brand takes Woodrow Wilson to the Marshlands art show. 
Food and drink:
Dr. Hopper is the name of a carbonated beverage created in the  Confederate States in the years after the Second Mexican War. By the time of the Second Great War, it is a widely popular drink among all Confederates, both black and white. It is likely an analog of Dr. Pepper.
Mason's Arms, a London eatery owned by Michael Stephanos.
Garuda, made in the Sultanate of Delhi (and named for the mythical bird), and popular the world over. 
Ochipway, made in the Sunset Lands. Pontiak, made in the Sunset Lands, popular as a limousine model, among other things. Possibly an analog of the OTL Pontiac. 
Abd-al-Latif and Sons, based in the Sunset Lands. Their elevators can even be found in the backward Grand Duchy of Italy. 
Bank of , an analog of numerous London, Victoria, and Alexandria OTL firms named "Bank of London and _______".
Bedrock Storage, Ltd.
Josiah Stanage Brewing Company, Ltd., owned by Phineas Stanage. Precious Treasures Storage Corporation, Ltd.
Food and drink:
John Adams Ale, named for John Adams, an 18th-century figure of North American Union history. Analogous to the OTL Sam Adams brand, named after John's cousin Samuel Adams.
Quiet Writer, one of the most common brands in the North American Union.
Worldwar [ ]
Borogove Engineering, a Los Angeles firm which employed Karen Culpepper as a receptionist in 1965. 
Helen Yu's: a Gardena Chinese place favored by Karen and Jonathan Yeager. 
Gold Lion Furniture, the business in Jerusalem which employed Deborah Radofsky as a receptionist in 1965. 
References [ ]
, p. 407. Atlantis and Other Places
, p. 69. The Case of the Toxic Spell Dump
↑ Ibid., pgs. 29-30.
↑ Ibid., p. 143.
, p. 2. The Case of the Toxic Spell Dump
↑ Ibid., p. 158.
, pg. 61. The Disunited States of America
↑ Ibid., pg. 25.
, mmp. pg. 11. The Gladiator
, p. 121. Counting Up, Counting Down
, pgs. 179-180, HC. A Different Flesh
, p. 698, HC. 3xT
3xT, p. 97, HC.
, p. 73. American Front
Inconsistencies (Southern Victory)
, pg. 15, HC. Through Darkest Europe
↑ Ibid., pg. 91, HC.
↑ Ibid., pg. 47, HC.
, p. 332, HC. Aftershocks
↑ Ibid., pgs. 332-333, HC.
↑ Ibid., p. 346, HC.