Here’s an interesting BusinessWeek article about spyware — specifically, about a company called Direct Revenue that has “generated sales of about $100 million since its start in 2002” by burrowing “into nearly 100 million computers” and producing “billions of pop-up ads.”

Direct Revenue’s spyware works by installing code on your computer.

Once embedded in your hard drive, spyware communicates via the Internet with the company that produced it. The company’s computer keeps track of your online meanderings and sends you pop-up ads relevant to the sites you visit. The travel-booking sites Travelocity (TSG ) and Priceline.com (PCLN ) have both been direct customers of Direct Revenue. People who picked up Direct Revenue spyware and then perused flights on Travelocity might find their screens obstructed by a pop-up for Priceline, or vice-versa. The travel sites say they stopped doing business with the company earlier this year.

The problem — as many people have learned — is that the software can be next-to-impossible to get rid of — and it can totally disable your computer. One application the company developed, called Aurora, was so troublesome it cost them customers — although it generated some nice virtual karma, too:

Even Aurora’s creators fell victim as the program froze computers at Direct Revenue. One sales staffer, Judit Major, documented receiving more than 30 pop-up ads in one day, according to e-mails. Her computer crashed four times. “We are serving WAY TOO MANY pops per hour,” wrote Chief Technology Officer Daniel Doman in a June e-mail to the company’s brass. “If we overdo it, we will really drive users to get us the hell [off] their machine. We need to BACK OFF or we will kill our base.”

Too late, guy.

Many major companies, such as Cingular and Yahoo, have severed connections with Direct Revenue.

Not everyone has, though. The article mentions Vonage as one company that remains a Direct Revenue company. Boo, Vonage.

I hate pop-ups myself. I avert my eyes from them on principle ;-)

But in a way, Spyware is but an extreme example of the attitude most software companies have toward our computers. They all try to install stuff without users necessarily understanding what it is and how it will change their interfaces or system performance.

I just downloaded a new version of Yahoo Messenger, for example, and had to uncheck a bunch of boxes to stop them from doing everything from making Yahoo my home page to messing around with my toolbars. Would the average person know to do this? Probably not. I do, because I’ve had to uninstall their stuff in the past. So I’ve wised up. But IMO, they shouldn’t be trying to sneak that stuff by in the first place.