Get your people to select and AGREE on dates to schedule conference calls, meetings and events. agreeAdate saves you time and money by avoiding telephone and email tag to find when people are free. Just send invitations to collect availability and then make your choice from the results.
This site bills itself as the easiest way to create amazing online invitations. Also links with Twitter and Flickr.
This site is probably the simplest to use for choosing common meeting times. It's other advantage is that it doesn't require creating an account. Just use it and go.