Want to know how long it will take you to become a millionaire? Want to know what your bank account or utility stock will be worth in 10 years assuming a certain return? Want to know if you can retire? There is a site which allows anyone to post and / or download Microsoft Excel templates and worksheets relating to stocks, trading, investing, and real estate called 18stocks.com.
The templates are unprotected so that you can go in and make changes, such as adding additional columns, etc., and you can do various 'what-ifs'. If you have your own template that you want to share with others, you can post it also. You would then become a published software author! (No pay of course, since you would be posting freeware.) By the way, when you post a template, I noticed that it takes 24 to 48 hours to appear on the list of available programs.
So if you want to know if you can retire, you can check out the Retirement Analyzer at 18stocks.com.