Bill Jelen 
Learn Excel from Mr. Excel [PDF ebook] 

Containing 277 business case studies that illustrate nearly every aspect of Excel, this book presents real-life business problems and works them through to their solutions. In addition to exemplary solutions, each case analysis considers alternate approaches and gotchas, and includes a summary of the necessary commands and functions. Excel files that can be downloaded and worked through step-by-step are included for each case.