There is a Free Downloadable Spreadsheet that will help you keep track of your saving.
This can also be ultimately uploaded back to google docs. This is awesome is you don't have the software you need to manipulate a spreadsheet..
I love googledocs. I use the google calendar too. I just discovered it...you can actually use it online or off line.
Here is the link to the spreadsheets.
There are directions how to download so you can use them.