Experiencing Google Spreadsheets
With Google Spreadsheets, you can work your worksheets from any computer in the globe as long as it is connected to the net. You can share the work with other co-workers or everybody else. And it's free!
However, since it saves the work automatically, you won't find quick responses for your instructions :( (or is it because of the slow internet connection here?). Either, you can't publish your worksheet directly to your blog :( Quite different from Google Docs. After all, Google Docs & Spreadsheets is a significant substitute to similar softwares available.