Google recently added a very cool feature for Google Spreadsheets. You can now create forms to collect data and have it automatically entered into a spreadsheet.

You can read more here: http://googledocs.blogspot.com/2008/02/stop-sharing-spreadsheets-start.html

Also with Google Docs you can embed a spreadsheet or chart into any webpage, and you can even set it to update in real time with every change made to the document.