My first major program was a DOS accounting program.  I wrote it from the ground up:

DOS Accounting Screen Shot

· User Interface

· Memory Manager

· Background Printing

· Database System

· Point Of Sale

· Inventory Control

· Payroll

· Etc.

 

Here are some Screen Shots and a Manual..

 

Today Windows does a lot of this for us, but I have a few ideas that may make bookkeeping easier.  ;-)