Admittedly, History librarian positions are Exceptionally rare.
Most of the time, the history librarian is really the "Humanities Librarian" or "Social Sciences Librarian" and they work with many departments.
At Drew University, I worked with ~10 departments as a librarian. At Portland State, I had 5.
Getting to work exclusively with History is the reason I came to W&M, and there are maybe(?) three dedicated history librarians in the entire country.
That said, there are always interesting history-related jobs within librarianship.
Academic Jobs
AHA Joblist. This is an obvious first step when looking for "traditional" university positions in History. Though mostly university positions, there are public history, library, museum, and archival openings are in there as well. It also includes some random-ish posting, like postings for an "Academic Technologist for Digital Scholarship."
History News Network Job Board. Like AHA, another great place to look. Includes professorships, postdocs, and other academic-related positions (and sometimes a Deanship!). Note that it sometimes takes a while for job list to load.
National Council on Public History. Excellent source for both non-university and university positions. Includes: Museums, historic sites, archives, libraries, gov researcher, non-profit researcher, admin, and digital humanities.
H-Net Job List Another staple for historians looking for history-related positions. You can narrow the search by your field using the keyword search and/or by using the assigned subject terms (these are listed in the posts themselves). In addition to professorships, it has a number of public history, archival, library, museum, and curatorial postings - sometime posted under the categories of "other" or "none." I also strongly suggest you all sign up for the weekly H-Net job posting listserv (and, indeed, sign up for the H-Net lists related to your interests).
Chronicle of Higher Ed Vitae Clearing house of academic positions generally. Search for "History" or "museum" or "archives" or "libraries" etc. Postings here will often overlap with previously mention lists, but it will also have unique postings.
Library/Archives/Museums/Public
ALA Joblist. Mostly Library jobs,
but not exclusively. There are many research-oriented positions, as well as museum and Public History postings. There are also a number of gov/non-profit/private/
corporate research positions advertised here. A library degree is
not always required for all the posted jobs - I found my previous position as a [nonpartisan] government researcher through the ALA Job list, and an MLS/MLIS degree was not
required.
INALJ. Mainly for librarians, but there are some non-library, non-MLS positions posted in there, mostly in public history or general research. Suggested search terms in the left-hand side bar include: archivists, data interpreters, catalogers, information officers, managers, curators, database admin, digital curation, indexing, general researcher, etc. These give you an idea of the jobs posted here.
LITA. Mainly for librarians, but a number of "Research Specialist" postings as well.
Government Research Positions
Some of you may be interested in using your research skills for government research (e.g. Library of Congress / Congressional Research Service / ND Legislature / etc). I can say from experience that there is a desire for trained, research-oriented historians in government at all levels. For gov research positions,
USAJOBS and the
Congressional Research Service are useful. When searching USAJOBS, use search terms like "history," "historian," and "researcher."