I'd recommend using a proxy server to browse the web, and setting policies limiting what can legitimately be accessed. There are several commercial ones, including ones from Microsoft and Netscape.
Public domain proxy servers include squid, and with perl, you can even build your own, using http proxy modules.
Offense, like beauty, is in the eye of the beholder, and a fantasy.
By guaranteeing freedom of expression, the First Amendment also guarntees offense.