I think NET NANNY is the best software...

Use of search facility provided by websites like youtube safe search for filter search while children use, addons for blocking unnecessary content, Facebook and many other social sites provide facility of report problem on any harmful content.
These are some tools which we can use daily...

dansgauardian.k9(windows).poenDNS.squidgaurd,hostsfile are best content filtering tools

http://dansguardian.org/

Net Nanny
„Ï Features: „« Content filtering „« Internet usage policies apply to devices on/off network „« Web-based admin and reporting „« Email alerts for policy violations or change requests „« Customized policy settings and rules „« Web content filtering „« Malware detection „« Bandwidth shaping management „« Peer-to-peer detection „« Active Directory integration „« 100% Cloud-Based „« Web content filtering

Themeforest.net having many wordpress based forum and other responsive ( which works on all devices) engine. http://themeforest.net/item/forumengine-flat-responsive-wordpress-forum-theme/5999646?WT.oss_phrase=&WT.oss_rank=30&WT.z_author=enginewpthemes&WT.trending=trending&WT.ac=search_list

This is one of the example.

There free open-source content management called WordPress & it is having many plugins of content management, blog and forum. No need to purchase specific product for this task.

It is really tough job to filter all the net contents.
Apart from doing that one another way to check it is suggested here: All the Internet service providers should be forced to follow norm based rules.
Every user would be allowed to access network through a password protected account only; just like goggle account which would be accessible through OTP.
Or only safe surfing should be allowed by provider in general, and OTP would be required when all the contents are to be watched

Adapting big data is one of the solution for text based content

I don't find any available tools for all the rule. But definitely we can build such framework.
For images, we can use nude.js file.