When Is Good is a tool that does one thing—helps a group of people choose the time for their next meeting or event. One person starts by clicking (or clicking and dragging down) all the times that they are available on a calendar grid that shows 2 1/2 weeks of time slots. When Is Good then provides a link to circulate to participants, who see the proposed times and click on when they are free. Whoever started the calendar gets to see the combined results.

http://whenisgood.net/