Have you ever counted the number of digital come-ons you receive daily? Just prior to writing that sentence, I noticed two more pieces of junk e-mail in my inbox. On average, I'd say I get 30 spam mails per hour. That's 720 per day, or more than 260,000 per year. Harrowing though that is, sadly, it may only be the beginning.

That's because of a scheme cleverly nicknamed spim. It's just like spam, except spim is delivered through instant messaging. I use Yahoo!'s (NASDAQ:YHOO) Messenger, Microsoft's (NASDAQ:MSFT) MSN Messenger, and Time Warner's (NYSE:TWX) AOL Instant Messenger, so I'm a prime target for spim.

Fortunately, the authorities seem to want to pounce on the problem before it really erupts. According to a report from News.com, 18-year-old Anthony Greco was arrested last week for allegedly sending out more than 1.5 million ads for pornography and mortgages to members of an online community called MySpace.com. News.com says Greco used MySpace.com's instant messaging service to conduct his campaign.

Forget the odd pairing for a minute -- but, really, porn and mortgages? -- and focus on the volume. According to a press release from September, MySpace.com boasts 4 million members. That means Greco hit, on average, at least one of every three members with some sort of digital come-on since he began spimming last autumn. And if that wasn't bad enough, Greco apparently threatened to up the volume by sharing his spimming methods with others unless MySpace.com agreed to a marketing deal that would have legitimized his campaign. Authorities nabbed the teenager last week after a sting operation led him to believe MySpace.com had accepted his terms, luring him from New York to Los Angeles. It was the first spim-related arrest in the U.S.

Color me cynical but I think this is far from over. Online communities are a dime a dozen on the Net, and it's only a matter of time before corporate networks using IM become targets. That ought to be troubling to big players like Yahoo! and AOL. But an old friend and former technology reporter with whom I discussed this story reassured me: The beauty of IM is that each program is capable of establishing buddy lists. Set up each program to accept only those messages coming from "buddies" and -- bingo -- problem solved. Yet I have a hard time believing it will really end that well. After all, I've used IM to reach out to colleagues who didn't have me on their buddy lists. What if I had been blocked?

Investors needn't stay up nights worrying about spim. But, long-term, an answer will need to be found. Rule-breaking hypergrowth opportunities are becoming rare on the Net; IM is one of those few still in its early stages. For those keeping an eye on Yahoo! and Microsoft, or who are desperately holding out for a resurgent AOL, spim is as much a threat as spam ever was.

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Fool contributor Tim Beyers sometimes thinks he's a little too addicted to IM. What's your favorite technology, and what investing opportunities does it present? Share your ideas at the New Paradigm Investing discussion board. Tim didn't own shares in any of the companies mentioned in this story at the time of publication. You can find out what's in his portfolio by checking Tim's Fool profile, which is here. The Motley Fool has a disclosure policy.