Yes, it's that time of year again. The day after Thanksgiving has traditionally been the start of the holiday shopping season. Retail monitoring specialist ShopperTrak estimates that $7.2 billion was spent during last year's Black Friday, a nearly 5% improvement from the 2002 showing.

That means that those of you with back problems may want to be careful when you step outside on Thursday to pick up your morning paper. It is usually loaded with store circulars promoting their early-bird deals. However, that doesn't mean that you need to break your back by dragging yourself out of bed in the wee hours the next morning to line up early for your holiday shopping.

Every year finds more and more traditional retailers offering up their Black Friday blowout deals online. The chains may have been skeptical at first. Discount department store giants Wal-Mart (NYSE:WMT) and Kmart (NASDAQ:KMRT) actually went back to the drawing board more than once in launching their online storefronts. Others such as Target (NYSE:TGT) and Toys "R" Us (NYSE:TOY) eventually handed over their sites to the proven e-tailing prowess of Amazon (NASDAQ:AMZN).

The online shopping migration is real. The world's leading retailer, Wal-Mart, grew its sales by 5% last year while Motley Fool Stock Advisor newsletter recommendation Amazon rang up a 34% spike in sales. Online upscale jeweler and Rule Breakers pick Blue Nile (NASDAQ:NILE) has grown its top line by 32% this year while the leading jewelry chain Zale (NYSE:ZLC) saw its sales climb by just 4% in fiscal 2004.

While that doesn't mean that the malls will be a whole lot less crowded this Friday it does mean that as a consumer -- and an investor -- one can't simply ignore the fact that online retailers are nibbling away at the market share.

So while you are bound to see endless footage of folks duking it out over bargain-priced DVD players and Elmo dolls, maybe it's time to replace the Ready, Set, Shop! mantra with Ready, Set, Click!

How is Amazon shaping up for the 2004 holiday season? When will its growth rate slow to that of traditional retailers? All this and more -- in the Amazon discussion board. Only on

Longtime Fool contributor Rick Munarriz has been an Amazon customer since the 1990s -- but he does not own shares in any of the companies mentioned in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.