Hi, DonMinter!
As programmer (VB and other letters) I rathter prefer a database (if not mainframe, then SQL, Access) than an Excel file. But I found Excel a so powerful and widespread tool, that sometimes I found myself opening Excel, pressing Alt-F11 and inserting a module, as the first action to face an issue.
Always data-administration focused and only exceptionally data-presentation focused, so charting has been a secondary feature not used a lot, just as needed.
And when I see articles or files like the one dan_l posted, I whisper to myself "wow... I want to do that", so I think I'll be -reluctantly at the beginning and hope smoothly after- walking into charting art.
Regards!
PS: I know remember a chart challenge that I found here, it resulted in a nice exercise, even it has nothing of charting but tracing. Give a look at this: http://chandoo.org/forums/topic/anyone-attempted-to-create-this-using-excel
PS2: Hui has many amazing charting and graphic things made too, here's the link to some of them: http://chandoo.org/wp/about-hui/
Don't miss 3D pendulums!