Some free and/or open source applications that can replace Microsoft Project:
GanttProject
Desktop-based.
http://www.ganttproject.biz/
LibrePlan
Web-based.
OpenProj
Open-source
https://sourceforge.net/projects/openproj/
Redmine
Open-source. Written in Ruby.
Projectlibre
Among the non-free, there is other software like Microsoft Project or Agilefant.