I founded, and host, an annual conference called Gnomedex, which brings together tech enthusiasts from across the globe, highlighting present and future trends as we see them taking shape. My wife/business partner helps produce it, and we have just hired an event manager for help in coordinating efforts.
As an integral part of getting an event of this size off the ground, I have a spreadsheet to store conference contacts and budget calculations. With Google Docs, I have been able to share this important info with various associates whenever they need the information. It's much easier than having to look up the accounts one by one, then pasting them over and over again into an email or instant message -- where the information would remain disorganized in any event (no pun intended). Also, keeping them stored online via Google Docs allows me to keep my hard drive cleaner, and not worry about the need to back them up so they are never lost (which would be disastrous when organizing a conference of this size).
Never having to ask if I'm looking at the latest version of a document or spreadsheet in the middle of the inevitable fire drills that accompany organizing Gnomedex? It's a dream come true. I don't have to worry about saving something, backing it up, copying it to multiple machines or anything of that nature. I simply create, save and be done with it.