These are resources, not necessarily recommendations (though for some tools I've written a glowing review). Some are free and others are free to try then require purchase. Please check them out and decide for yourself if they will work in your classroom.
Using Google Sheets to Make Timelines - great example of using DLCS in the content area
American Panorama - an atlas of U.S. history through maps
American Social History Project - "...challenges traditional ways that people learn about the past with its print, visual, and multimedia materials that explore the diverse social and cultural histories of the nation."
Podcast response pages and this list or this list of podcasts
Juxtapose - a tool that creates an interactive visual of how a place looked at two different times