Dudle - Dudle is an online scheduling application, which is free and open source.
Taskable - Using multiple work apps leads to tons of context switching, breaking flow and killing productivity.
Pulse 24/7 - Booking & scheduling mobile app for service providers
Motion Firefox - All-in-one time management tool in Firefox
MakePlans - Online appointment booking - MakePlans
TideTask - Control your procrastination and never miss a task again