A thermometer chart is a great way of visually showing the percentage of task that is completed or progress towards a specific goal. View the video demonstration below to learn how to create your own thermometer chart in Excel 2007.
What you will need to do is create a chart that uses a single cell reference as a data series (this will be your percentage).
You will then do a little formatting and tweaking of the Data Series (gap width to zero) and Axis options (minimum zero and maximum 1). Insert a textbox and link it to your percentage value (insert > textbox> (draw box where you want it) > F2 > =(select % value cell).
The rest is just cosmetic and you can play around with Excel's formatting options to suit yourself.