Comodo DNS is also good. It's based on ultraDNS and even uses some of the same servers. It doesn't have all the options though, in fact it doesn't have any but it does block some known bad sites and has no advertising when you get an error. It just shows a Comodo page and tells you that the site is either unreachable or has been blocked. It's not quite as fast as OpenDns or Level 3 for me but the difference is very small according to the DNS benchmark tool by Steve Gibson.