Excel is vast: it covers so many areas of expertise I doubt there's anyone familiar with every aspect of its application. 

Please note: These products are NOT for sale. They're examples of some of the work I've done for companies as diverse as Novo Nordisk, Investec, and Rentokil. 

Guest Survey Database

You can go a long way with Excel's built-in tools and features, but if you really want to go the distance, you have to be able to code.

The Guest Survey Database runs on VBA (Visual Basic for Applications). Everything from the interface to the creation of pivot tables is generated by code.

The pulldown menus let you choose a date range, then filter the data for different venues.

Dose Loading

A drug's half-life is how long it keeps circulating in your bloodstream. Some medications are designed to have a half-life of weeks. If a doctor wants his patient to have a certain amount of the chemical in his body at all times, he must work out how much to administer and how often. This is calculated with a formula. 

Cancelled Revenue

Some service industry businesses have different divisions with each division having many branches. Some of these businesses also have a high client turnover. Clients switch service providers for different reasons: they've got a better deal, they're unhappy with the service, etc.

This dashboard tracks which branches in which divisions are losing the most revenue.

Sensitivity Analysis

This chart calculates how long it will take a startup to break even, based on the percentage of revenue growth and the percentage of expense growth.

It uses conditional highlighting to move the beige vertical and horizontal highlighting bars so they overlap on the number of years.

Variable Interest Rate Calculator

An Excel widget is a mini-dashboard dedicated to performing one task and one task only.

By changing the values in the box at the bottom right, this widget lets you calculate how much you will have to repay on a loan or how much you will earn as the return on an investment.