It’s is a great program so long as you know how to use Excel. You can use it for all sorts of things, well beyond the original idea of a spreadsheet.
But this power has a problem associated with it: learning how to use Excel beyond the basics isn’t easy.
Even if you consider yourself a power user, chances are that you’ll learn new tips and tricks in How to Use Excel.
More about How to Use Excel
The How to Use Excel tutorial comes in PDF format, which makes searching a lot easier than flicking through a printed index and hoping that you and the book’s author agree on terminology.
If you’re not sure about some of the basic aspects of Excel, these are covered but the main emphasis is on speed of use. 
If you’re using a program such as Excel on a regular basis, you’ll know that there are a handful of things that you use near enough all the time. And it’s here that this tutorial comes into its own…
As you doubtless know, you can format cells so that they look different and show up nicely on screen. But this tutorial shows you how to format them “on the fly” as you’re typing, without navigating the menu system.
Error trapping is essential when you’re using a spreadsheet. The tutorial talks you through how to use Excel’s built in form capability to streamline this as much as possible.
Another time saving trick lets you easily access different worksheets.
You’re also shown how to set up custom views for your spreadsheets as well as copying styles across workbooks.
All in all, the tutorial is excellent and I discovered an embarrassingly large number of tips and tricks that I didn’t know about Excel and I’ve been using the program to do lots of work over a number of years.
The tutorial covers Excel 2003 and Excel 2007, so whichever version you are using will be covered.