My fellow Fools and I have been preoccupied with Amazon.com's (NASDAQ:AMZN) digital plans lately. But on Monday, the company announced another unusual-sounding acquisition: a retail Web site called Shopbop.com. It seems to me like an uncharacteristic move for the e-commerce giant.

Shopbop.com specializes in women's clothing and accessories, peddling 75 designer brands such as True Religion (NASDAQ:TRLG), Liz Claiborne's (NASDAQ:LIZ) Juicy Couture, Diesel, 7 for All Mankind, and Marc Jacobs. (If some of those names made you think of the high-priced denim that has been so hot lately -- bingo.) Terms of the acquisition were not disclosed.

The timing of Amazon's acquisition of Shopbop.com seems odd, especially after the company reported a quarter that left many investors cold, and especially since it's a departure from Amazon's usual acquisition strategy. Until now, Amazon has been content to serve as a virtual shopping mall for other clothing retailers, like Nordstrom (NYSE:JWN), Chico's (NYSE:CHS), and Coldwater Creek (NASDAQ:CWTR), for example.

It's interesting to note that Shopbop.com, which has been around since 1999 and is based in Madison, Wis., won't be under Amazon's virtual roof at all. Like the Internet Movie Database (better known as IMDb.com), Shopbop.com will continue to operate as a standalone site.

Although Internet retail is Amazon's forte, I'm having a hard time imagining how Shopbop.com might fit into its overall worldview. After all, IMDb.com segues well into Amazon's A9.com search engine, and at some point it could drive customers to an Amazon DVD rental store (if such a thing ever comes to pass), if not a digital downloading service. Amazon's Alexa.com is another Web search engine that gets little attention, despite its interesting side job: tracking website traffic. I can imagine that this nifty little site has its own possibilities for boosting Amazon's usefulness at some point.

Meanwhile, the Shopbop acquisition might seem a bit ill-timed, considering investors' recent concerns with Amazon.com (well-reflected in its stock price as of late).

Then again, Amazon's got a reputation for a lot of smart moves over the last 10 years or so, despite occasional bouts with investor skepticism (click here to read a recent duel two Fools had over Amazon). Although I can't help but ask these questions, I certainly wouldn't bet against Amazon having the right answers over the long term.

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Alyce Lomax does not own shares of any of the companies mentioned.