Google has added a new option to Google Docs and Spreadsheets to make files open for others to look at without the need to register or sign in with a Google account. To make any doc or spreadsheet open, users can click option for "invitations may be used by anyone" in the "Share" tab. Once enabled, any invite to view the spreadsheet will take users right to it, bypassing any annoying log-in screens. Users will still need to log in and be on the collaborators list to make any editing changes, but this should open things up for the select few who don't use Google's services.
Google is also allowing Google Apps users to share documents outside of their domain. Previously, only members of that domain were able to view and make changes. Opening up docs and spreadsheets to outsiders is still controlled by the group administrator but is a big step forward for small groups who want to share their work with others without having to export it to another format or service.