April’s GeneaGem is definitely not an April Fool’s Day prank!
PastPerfectOnline invites readers to “view millions of artifacts from hundreds of museums, library, and archive collections.”

At the top left corner, click on List of Collections:

A very lengthy list of 900+ collections, helpfully grouped by state, appears.
There is a huge variety available, ranging from the Texas Czech Heritage & Cultural Center to the American Precision Museum in Vermont to Wisconsin’s Norwegian American Genealogical Center and Naeseth Library to Museum of Chinese in America, based in New York.
Although I highlighted several websites with clear genealogical connections, there are all types of museums, historical societies and libraries to be found in this list. Not surprisingly, some links lead to robust collections while others – not so much.
This is a fun website to browse – you never know what you’ll find!
The museum/archive where I volunteer uses PP and has all its photographs up online… The software is definitely old, but still reliable.
I knew about PastPerfect, as we use that program at our historical society archives and have been entering data for putting online. I see we are not in the list, so I guess we haven’t made it public yet. Another good source for California research at museums and archives is the Online Archive of California, which we do have a presence.