Neatline
This is an Omeka add-on that facilitates the creation of both maps and timelines.
“Neatline is a geotemporal exhibit-builder that allows you to create beautiful, complex maps, image annotations, and narrative sequences from Omeka collections of archives and artifacts, and to connect your maps and narratives with timelines that are more-than-usually sensitive to ambiguity and nuance” (“What is Neatline?”).
TimelineJS
“TimelineJS is an open-source tool that enables anyone to build visually rich, interactive timelines.”