In December 2009, Google publicized their new public DNS resolution service; a week later, they also announced the open-source release of a DNS benchmarking tool called namebench, a DNS benchmarking tool. It is designed to "hunt down the fastest DNS servers available for your computer to use."
Since web traffic is measured in milliseconds, delays of 200-400ms for slow DNS resolution can be more meaningful than it would seem. Using namebench to benchmark a variety of DNS servers, it is possible to speed up browsing by finding a faster DNS resolver.
You could write a script to test DNS resolution via nslookup, or a similar query tool; however, namebench includes several interesting features: it uses your browser history to select a list of hosts to test against, appropriately handles multiple IPs of cache-sharing resolvers, and reports on resolvers that use DNS hijacking. At the end of its benchmarking process, namebench suggests which DNS resolver seems to be the fastest, and displays useful statistical information about the test results.