While catching up on my reading, I came across this a post by Seth Godin called "They Didn't Get the Memo."  Numbers 1 and 5 jumped out at me.

1.  31.4% of Americans don't have internet access.
5.  30% of internet users in the US use a modem.

According to the CIA (they should know, shouldn't they?) the United States has about 296 million residents.  For the sake of this, ONLY, we'll call them Americans.  That means that about 96 million Americans don't have internet access.

Of the 200 million with internet access, 60 million of them are on modems.

How many of your clients fit into that 60 million?  Bells and whistles and flash presentations are nice, but if you want those modem users to stick around your website, remember the KISS method.  Keep It Simple Sonny, or Sister, depending on your preference.

Between the no access and modem access, that's 156 million people who potentially cannot or will not spend time on your website.

When building or maintaining your website, never forget that 30%.  If you do, it will effect your business. AND, while you are building your marketing plan, remember the 31.4%.  They are the reason print advertising will never die.