Google Public DNS

8.8.8.8
8.8.4.4

Level 3 Public DNS Server Addresses:

209.244.0.3
209.244.0.4
4.2.2.1
4.2.2.2
4.2.2.3
4.2.2.4

OpenDNS IP Addresses:

208.67.222.222
208.67.220.220

Open-source DNS Benchmark Utility
https://code.google.com/p/namebench/