Welcome to the Daily 5, our lighthearted look at the business news that amuses us.

Yesterday, social-networking superstar Facebook held its developer conference in San Francisco. To commemorate the event and the introduction of Facebook Connect -- a single sign-in system that's roughly equivalent to Microsoft's (NASDAQ:MSFT) Passport, but for the social Web -- we take a closer look at social networking generally, and the digital heroin known as Twitter specifically.

Here are five signs that you might be addicted to this (ahem) "micro-blogging" service. Drumroll, please:

5. Your doctor prescribes a daily diet of triple-shot espresso as a relaxant.

4. You actually know a guy named darthvader.

3. Latest entry: "flushing."

2. You binge on Facebook (or MySpace, or LinkedIn) every time Twitter suffers an outage.

And the No. 1 sign that you're addicted to Twitter ... You just changed your middle name to @.

The book on Facebook
Twitter may be extreme, but as a concept, social networking is pure Web -- born of the network effects model that eBay (NASDAQ:EBAY) pioneered. To us, it's a business tool in the making.

Think about it: There's a thin line between Blue Nile (NASDAQ:NILE), The Knot (NASDAQ:KNOT), and LoopNet (NASDAQ:LOOP) and Facebook, MySpace, and LinkedIn. Every one of them is social in some form. MySpace unites music fans; Blue Nile unites the soon-to-be-betrothed. And the big money is betting on both.

See anything we missed? Have a different take? Post your thoughts in the comments box below. 

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Neither Fool contributor Tim Beyers nor Dayana Yochim owned shares in any of the companies mentioned at the time of publication. Tim seeks the best of the tech as a member of the Motley Fool Rule Breakers team. Get a daily dose of his Foolish musings via this feed for your RSS reader.

eBay is a Stock Advisor selection. Microsoft is an Inside Value pick. Blue Nile, LoopNet, and The Knot are Rule Breakers recommendations. LoopNet is also a Hidden Gems pick. Try any of these market-beating services free for 30 days. There's no obligation to subscribe.

The Motley Fool's disclosure policy was Joe Cool long before Snoopy stole the idea.