chat feature in spreadsheets and presentations or the integration of Google Docs with other apps (you can schedule an event in Google Calendar from a doc, you can integrate a doc in the brand new Google Sites wiki-like application, you can transform a Google Notebook into a doc, you can use a Google Spreadsheet as a web-based bookmark storage thanks to its integration with Google Co-op subscribed links, you can also published in Blogger directly from a doc, you can use a Google Doc spreadsheet template to upload a complex Google Earth map - see Google Earth Outreach, you can access from Gmail a Google shared spreadsheet even if it has been sent as attached email, etc.)