Pick - The simplest way to schedule a time to meet
Loomio - Loomio helps groups of people make decisions together, online.
Meekan - Connecting the world's calendars
DemocracyOS - DemocracyOS is an open source application for online decision making.
LettuceMeet - The easiest way to schedule group meetings.
Airesis - A decision making tool for direct democracy and e-government: participate in discussions, bring your ideas, suggest solutions and vote online