Change DNS Helper is a free tool which makes it easier to manage your preferred DNS servers, possibly improving performance and security, and giving access to sites you couldn't reach normally.
Switching your DNS requires a minimum of 3 steps: choose your adapter, select a DNS server (Google, OpenDNS, Comodo, Yandex, Norton and assorted others are supported) and click "Change DNS".
Unusually, you can also choose to set your DNS server for IPv4 and IPv6 connections separately.
There are options to reset, back up and restore your DNS settings, handy if the program hasn't worked as expected.
Need support for another server? You can add whatever you need by editing an INI file. It's a simple format: name= and the IP addresses, like--
US - Google Public DNS=126.96.36.199,188.8.131.52
US - Comodo Secure DNS=184.108.40.206,220.127.116.11
There are other buttons, some of which carry out useful tasks (flush DNS cache, renew IP address), but others are a little more ad-related. Clicking "Hide IP Address" or "Fast VPN Service" opens the Hide My Ass site, for instance, and it's probably no coincidence that there's also a "Hide My Ass" ad on one of the tabs. But don't let this put you off. The program doesn't install any adware, its own ad isn't visible on the main interface, and once you learn which buttons open the website you need never click on them again.