http://typewith.me/ - Go ahead, try it. Send the link to your closest friends and colleagues. Collaborate with just about anybody, anytime. Don't just take my word for it. No registration required, no subscriptions to maintain. It's ad hoc team document creation at its finest - based on open source software (from a service that may disappear at any moment now that Google's acquired it for use with Google Wave).
And if you happen to catch anybody saying "It's like Google Wave" in the comments here, feel free to call them a DUMBASS - because Google Wave: (a) requires registration, and (b) isn't as simple for everybody to use for simple document collaboration.
