OpenDNS is an incredible alternative to your ISP DNS server.  Simply put DNS (Domain Name System) translates IP address to easy to remember hostname's. Not only will OpenDNS make your browsing faster, there are a lot of additional features provided by this free service.

OpenDNS is free with no software to install.  It also has a bunch of features such as Phishing protection, Domain Blocking, Adult Site Blocking, Typo Correction, etc.  If you are behind a router the easiest way to ensure every computer on your home network is using OpenDNS is to add it to your Router. 

Open your web browser and go to your router's address.  Usually it is 192.168.1.1 type in the user name and password to access administrator settings.  For this example I am using a Linksys WRT54GS, yours maybe different but the entry is basically the same.  Under basic setup find your routers static DNS settings.  Type in 208.67.222.222 and 208.67.220.220 hit save and your done!

I highly recommend trying OpenDNS.  I have been using it for over 6 months now, and in fact I forgot I was using it until I mistyped a URL and OpenDNS told me that I was accessing a shady site.