OpenWRT is a fantastic open source distribution for embedded devices, such as the Linksys WRT-54G series of wireless routers. One of its many features is the use of dnsmasq, a combined DNS and DHCP server, useful on small networks that are sitting behind a NAT connection.
The downside of dnsmasq on OpenWRT, however, is that the default configuration uses your ISP's DNS servers, which can be problematic, if your ISP, like many others, is adopting bad habits of redirecting non-existent domains to their servers, or is blacklisting / censoring websites without asking you.
For this, and for so many other reasons, it's a much better idea to run your own local DNS resolver. Unfortunately, dnsmasq isn't cable of doing this, so it's necessary to install a DNS server that can do this on its own. In this article, I describe how to do this.