Ashgate
If you are interested in the Crusades, Byzantine studies, early modern gender studies, Islamic history, the Reformation, as well as intellectual history and the history of science and medicine, then you should take a look at Ashgate.
Berg
Berg tends to be trendy in its history. You'll find books on the history of Italian politics and food, Nazi fashion, or French football (soccer). You can browse online or request a catalog (and thereby get on their mailing list).
Blackwell Publishing
Blackwell offers excellent studies from ancient to modern history. It has some excellent series (including the Blackwell Essential Readings in History) that focus on women's and gender history, the social history of France, Great Britain, and the US, as well as ancient, classical, and Renaissance history. Blackwell is weak on modern southern European history. You can sign up for email alerts on general historical areas by selecting Blackwell Publishing Email Alerts.
Cambridge University Press History
Cambridge University Press is, obviously, one of the big academic presses that you should know, and its publications should be followed closely. CUP is particularly strong in British, American, German, and French history and early-modern Europe. Check out the Cambridge History Series that offers a volume on most countries. You can keep up with current works in your field by subscribing to CUP's email service, which will alert you to new publications in many fields. To enroll, click Subscribe to the Cambridge Email Service and fill out the form.
Chicago University Press
Be sure to check out Chicago University Press. Whether you're interested in American or European history, ancient or medieval, Renaissance or Early Modern, or the history of ideas or historiography, you'll find a treasure trove here. Be sure to check out their Asian history offerings and their reprint editions. Browse online, or register for automatic, electronic new release information.
Colombia University Press
Columbia University Press, like its counterparts among US academic presses, offers comprehensive offerings in history. Be sure to check out the African-American history offerings, the African history section, the Asian section, or the Central and Eastern European catalogs. You might try signing up for their listserv to receive electronic messages about new releases.
Cornell University Press
Cornell University Press is particularly strong in Asian studies, classics, Slavic studies, and women's history. You can sign up on their homepage to receive emails.
Duke University Press
You might not expect it, but Duke University Press is one of the largest academic presses in the US. It is known for its emphasis on cultural history, covering Asia, Europe, Latin America, and the US. You can request a catalog (and thereby get on their mailing list) or subscribe to email updates.
Harvard University Press
Harvard University Press is a major US university press and rivals the best publishing companies in the world. Browse their online catalog. It's truly amazing. You can also register to receive email about forthcoming books.
Indiana University Press
Associated with the other Indiana University, Indiana University Press specializes in (among other fields) African, African American, Asian, Caribbean, Latin American, Middle East, and Eastern European area studies, as well as the Civil War, the Holocaust, medieval and Renaissance studies, and women's and gender studies. Order or download a print catalog, or subscribe to one of their subject email lists.
Louisiana State University Press
Check out the gems that Louisiana State University Press publishes on the Antebellum South, the Civil War, World War II, the Caribbean, and French history.
Manchester University Press
Manchester University Press (MUP) has an exhaustive catalog of (mainly) British history and important offerings in medieval history. It also has excellent works in cultural studies and economic history. MUP does not have an email alert, but you can get on their print mailing list. Visit their site for more information.
Massachusetts Institute of Technology Press
Massachusetts Institute of Technology Press (MIT Press) is an invaluable resource to anyone interested in the history of science. You can join an email list here: MIT email list.
Michigan State University Press
Michigan State University Press specializes in American studies (the Midwest and Great Lakes region), Native American studies, women's studies, and even Canadian studies.
Northwestern University Press
Northwestern University Press will be useful to those interested in cultural history and Slavic and Russian area studies.
Norton
Norton has a reputable collection of US, European, and world history. Norton has substantial offerings in Latin American and Asian history.
Ohio State University Press
You'll want to check out Ohio State University Press if you're interested in the history of business, the history of crime, Victorian studies, or urban studies. As you might expect, it has a large offering in Ohioan history. There are internal links to order catalogs or sign up for email notifications of forthcoming books.
Oxford University Press
Oxford University Press (OUP) is an excellent resource for building your own personal library. Browse the history pages. Check out the collection of inexpensive literary classics. (You'll find links on the left side of the home page.)
Palgrave Macmillan
Palgrave Macmillan has a broad offering, something you come to expect from one of the larger international presses. Browse its extensive lists of African, Asian, US, Continental European, and British history, as well as its collection in the history of science. Sign up for email announcements on general topics here: Palgrave Mailing List.
Penguin Books
Although not strictly an academic press, Penguin Books has solid offerings in history, the humanities, and the social sciences. Click on the Browse Subject link at the top of the page and then click on the area "history."
Penn State University Press
In addition to books on Pennsylvania history, Penn State University Press offers works in American, European Medieval, and Latin American history.
Princeton University Press
Princeton University Press (PUP) had a truly comprehensive offering. In addition to excellent titles in US and European history, PUP offers important works in Asian history, the history of science and medicine, and comparative history.
Random House
Random House has a vast collection of historical works that span the globe, beginning in ancient history and ending in contemporary history.
Routledge
Routledge has an extensive collection of historical works. To get to History from this link, click on Catalogue and then follow the instructions.
Rutgers University Press
In addition to works in Asian, European History, US, and Latin American history, Rutgers University Press offers works on the history of medicine and science, the history of technology, and military history.
San Diego State University Press
San Diego State University Press currently has a post-modern website.
Stanford University Press
Stanford University Press offers studies in Asian studies and Asian-American studies, Middle East studies, literary and cultural theory, and Latin American studies.
State University of New York (SUNY) Press
SUNY Press offers titles in Jewish studies, Middle Eastern studies, Asian studies, and women's studies.
University of Alabama Press
University of Alabama Press specializes in American history (the South, African-American studies, Native American studies, military history, and religious history) and also publishes in Jewish studies, Latin American history, historical archaeology, and ethnohistory.
University of Arizona Press
A small press, the University of Arizona Press offers books in Native American studies, Chicano studies, and Latin American studies.
University of California Press
The University of California Press offers books on Asian history, the history of science, cultural and social history, Latin American history, and many other areas. Browse online or order a catalog. Check them out!
University of Illinois Press
The University of Illinois Press's offerings span the globe and cover most subfields of history (cultural, social, political, economic, area studies, etc.).
University of Michigan Press
University of Michigan Press has impressive titles in Classics, medieval and Renaissance history, and American history.
University of Minnesota Press
University of Minnesota Press's offerings in history are more social and cultural history. The press prides itself in its titles in race and ethnic studies, feminist criticism, and media studies. They are one of the few American presses to have a concentration in Scandinavian studies.
University of Missouri Press
University of Missouri Press offers an excellent collection of titles in intellectual history.
University of North Carolina Press
University of North Carolina Press has a solid offering in African American studies, American studies, Native American Studies, Appalachian studies, and Civil War history, as well as ancient, US, European, and Latin American history.
University of Notre Dame Press
The University of Notre Dame Press offers interesting titles in the history of the Catholic Church in a global context.
Yale University Press
Like the other university presses, Yale University Press (YUP) offers titles in African, American, Asian, European, and Middle Eastern history from leading historians. Browse their offerings online.