With Arduino shields and libraries it is really easy to connect device to internet. Probably many of you have already tried Pachube service for publishing data online. The downside of Pachube that it is fairly hard to extract data from it to spreadsheet that could be analyzed in our way.
Boris have shared his method of sending data from Arduino to Google Docs spreadsheet. The idea to access spreadsheet is to use Form from Google Docs which boxes are associated with spreadsheet fields. Then by using simple POST routine you can collect nicely arranged data table is spreadsheet which can be for your own needs.