The World Wide Web can open your eyes to material you didn't know existed. The trouble is, not all of that material is suitable for everyone's eyes. That's the argument for Internet-filtering software--applications that block access to potentially objectionable Web sites and prevent young 'uns from wandering into the Web's seedier neighborhoods. But perhaps they do their job too well. We installed three of the more user-friendly filtering applications: Content-Barrier, from Intego ($40; 305/868-7920, www.intego.com ); KidSafe, from Apple (free; 800/6927753, www.apple.com ); and AOL 5.0's parental controls (subscription prices vary; 800/827-6364, www.aol.com ). We used each program's most restrictive settings--turning on all 26 of ContentBarrier's filtering categories; selecting the Children 12 And Under filter in AOL's Web-surfing controls; and using KidSafe's default setting, which lets you visit only sites OK'd by a panel of educators. Then we visited sites that we thought were squeaky-clean. The results? Either the Web is a lot more risqué than we imagined, or Internet-filtering software needs a healthy dose of parental common sense to be truly helpful.