Highly available DNS
Read a sweet paper on DNS high availability using some router hacks. See ISC-TN-2004-1 here. Basically the F root server for the whole internet has the IP address 192.5.5.241, but there are servers distributed all over the world answering queries for that address. It’s similar to a load balancing device, except it is implemented by having multiple routers and switches pointing to your server cluster. There’s no cheesy load balancing device that is a single point of failure.
Apparently you could use this setup for other traffic types also, but it works really well for DNS because there is a single UDP request, and a single UDP answer.