WebLocker is a free tool which enables blocking ads, malicious websites, adult websites, social networks, gambling sites and more.
The program works partly by changing your DNS server. Choose the policy which matches your needs - whether you want to be more secure, improve performance, unblock US sites, stay safe from porn or keep your browsing family-friendly - and WebLocker updates your system with a click.
There are also separate tools for individually blocking porn, ads, gambling or social network sites, and an anti-DNS leak option. These may work by updating your HOSTS file, although the developer doesn't make it clear.
WebLocker can also block individual custom websites, either permanently or for the time you specify. You could make a site available only at the weekends, for instance, or just for a couple of hours in the evening.
Password protection ensures other users of the PC can't modify your settings.
While the program is free, we found it displayed a nag screen on launch and at other times, requesting "donations". But the message explained that this isn't simply for the developer, as 50% of your donation will go to "beggars". Good to know.