Cloud computing is the future. What cloud really mean? If you are using gmail then you are already using cloud. Ok another concept is create office files like spreadsheet and word online is possible now with google docs.
You can access it here ;- Click Here
Once you login with your google account you can basically see the friendly interface shown below..
You can click on > Create New > and select > spreadsheet if you want to create an excel type of document online.
The best thing about this is you do not need to have microsoft office install to use these productivity tool.However these are very basic ala excel clone. Dont expect full functionality of ms excel here but it is sufficient for most people.
Go ahead and give cloud computing a try!