Business 101: Procedures
Never did I think that writing procedures would be so crucial to running a successful business. But it is. Every task that is a "process" must be written in black and white and printed out. So that, should that staff member not show up, someone else can pick up the task. I suggest lots of screenshots of the steps required to complete the task. A step by step guide because, let's face it, most tasks are a very simple process of step by step mouse clicks.
Make sure the procedures are kept up to date and make sure at least 2 staff members know the procedure. Also pass around the procedures, you'll be amazed how lazy people get. Give that process to another person and they cut it in half with macros or code.