The security industry

Ideas

 * anti-malware
 * security bundles (firewalls etc)
 * content filtering

Examples of "parental control" / filtering software:
 * Bess (N2H2)
 * CyberSitter (Solid Oak Software)
 * CyberPatrol (SurfControl; top choice in the US)
 * Net Nanny (Net Nanny Software)
 * NetRated (PC DataPower)
 * Smartfilter (Secure Computing Corporation)
 * Surfwatch (SurfControl)
 * I-Gear (Symantec)
 * Websense (Websense)
 * X-Stop (f8e6 Technologies)

NB! It is a huge industry ONLY in the United States, while being next to unknown elsewhere (although censorship is present in many places, censorship industry as such is not).

All the abovementioned are proprietary software - the database being a "trade secret", the users have to solely rely on the producer's decisions on filtering.

Many cases of different agendas behind the filtering criteria.

Technical incompetence of filtering (the "breast" case etc)