Doodle is a brilliantly simple polling system that helps people coordinate times when they all can meet. There's no fancy Web 2.0 code. Just a simple grid with red and green squares that looks exactly like the spreadsheet my poker buddies and I use to find days to play. The link to a poll is just sent via e-mail; no sign-up is required.
Missing features? Yes, buckets of them: time-zone coordination, Outlook synchronization, privacy, you name it. And although replying to a Doodle poll is clarity itself, the interface for the meeting organizer isn't very pretty. But I don't care, and if you use it, you won't either, because it just works.
First spotted on 43 Folders.