Google seems to be testing a spreadsheet application.
http://www.google.com/googlespreadsheets/tour1.html
Add this to the Calendar and the E-mail application and it starts to look real bad for the other Office Application makers. ;-)
Yeah, I saw news of that and have read about some of its features. It actually does sounds like a pretty powerful application; I know I've applied on Google to try it.
But.. as for other office applications, I pretty much stick to vim, latex, email (gmail or other), and notebook paper (for calendars and other things). My backward ways often seem more productive to me. ;-P