Here are some of the resources that people pointed me towards:

– http://ganttproject.sourceforge.net (project management tool with timeline feature)

– other gantt chart tools, like http://echo2gantt.sourceforge.net

– MS Project

– Other, more free-form project organization tools, such as “Basecamp” at: http://www.37signals.com

– http://simile.mit.edu/timeline/ (simile timeline – this is what I think I’ll end up using)