Google Docs Spreadsheets is a free online app that creates spreadsheets which can be shared with other people. All that is required to use Google Sheets is a web browser on any operating system. If you are familiar with Microsoft Excel or Apple Numbers, you will be comfortable with Google Docs Spreadsheets.
Unlike Microsoft Excel or Apple Numbers, Google Docs Spreadsheets offers a wide array of financial functions such as current prices, fundamental stock data, and mutual fund performance. The financial functions can be embedded in a Google Docs Spreadsheet to provide nearly real time updates. For more information see the Google docs finance help page.
Click on the spreadsheet above for sample Google Docs spreadsheets to monitor your portfolio.