It's official: Yahoo! (Nasdaq: YHOO) has handed its search keys to Microsoft (Nasdaq: MSFT). Redmond's homemade Bing engine completely took over Yahoo!'s organic search operations yesterday.

The move should generate healthy revenue streams for Yahoo! -- at the likely expense of its brand and popularity. After all, we already saw what happened nearly a decade ago, when Yahoo! let Google (Nasdaq: GOOG) power its queries.

There's no going back now. Yahoo! seems entirely focused on display advertising at this point. That niche makes sense, given the volume of pages that the online pioneer serves up through its leading e-mail service and news hub.

However, Yahoo! investors will clamor for more than just graphical ads and fat checks from Bing. Armed with more than $4 billion in the bank, the company could use a good shopping spree to overcome its organic stagnation.

Unfortunately, $4 billion doesn't go as far as it used to -- and Yahoo!'s lackluster trading nixes its ability to use equity as a deal-sweetener. 

Acquisition targets are down to either promising small upstarts that won't move the needle, or larger out-of-favor companies -- think AOL (NYSE: AOL) -- that won't excite the market.

Yahoo! could also pad its coffers by selling its stake in China's Alibaba. The Chinese dot-com juggernaut has reportedly made overtures to buy back Yahoo!'s stake, a move that makes sense as Alibaba starts making stateside inroads. Alibaba is ready to launch a B2B marketplace in the United States, having acquired a pair of domestic auction services specialists in recent months.

In other words, Alibaba is growing into a competitor for Yahoo! in the U.S., and an outright thorn in eBay's (Nasdaq: EBAY) side.

Yahoo! and eBay? Now, there's a thought! Both companies have been uninspiring investments lately, owing largely to the failures of their flagship businesses. Yahoo!'s search engine and eBay's namesake auction site aren't what they used to be. Thankfully, Yahoo! is still a popular site, and eBay has PayPal.

One can't necessarily afford the other, since eBay's market cap of $30 billion and Yahoo!'s $18 billion price tag are prohibitive. However, there's enough wiggle room for some form of merger on an all-stock basis, because they're both in the same boat when it comes to humdrum equity.

Sure, this wedding would come many years too late, but it would definitely make the two dot-com laggards major players again. 

What do you think? Can Yahoo! and eBay work together? Share your thoughts in the comment box below.

Google and Microsoft are Motley Fool Inside Value picks. Google is a Motley Fool Rule Breakers recommendation. eBay is a Motley Fool Stock Advisor selection. Motley Fool Options has recommended a bull call spread position on eBay. Motley Fool Options has recommended a diagonal call position on Microsoft. The Fool owns shares of Google. Try any of our Foolish newsletters today, free for 30 days.

Longtime Fool contributor Rick Munarriz wonders whether it's time for Yahoo! to shed the exclamation point. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.