Catweazle is correct that there is very little that software alone can do. A company that I have been a customer of in the past and am currently partnered with at work (I work for a company that develops websites for churches) is Integrity Online. They offer a variety of services from filtered internet access to free accountability software (tracks and reports access to potentially inappropriate content). The nice thing is that their internet filters aren't mindless programs; rather, they are filters that are actively monitored and maintained by the company.