In addition to the above and since the poster actually said sample, I would add
Peter Noneley's Excel Dictionary, it is actually an Excel workbook ( zipped) with
actual examples of worksheet functions. You can obtain it on Ron de Bruin's
site at http://www.rondebruin.nl/files/xlfdic01.zip from http://www.rondebruin.nl/id.htm

and my favorite for quick introduction and limited in depth coverage (something for everybody)
see flash topics at http://www.datapigtechnologies.com/ExcelMain.htm

I can't view them in Internet Explorer, but I can view them and other Flash 8 presentations
in Firefox now that I have turned off (deselected) the "obj-tabs" from Adblock Options,
of course you could disable or remove the Adblock extension but that make many sites
unbearable. Most people don't seem to have the problem in IE or in Firefox.