One way enthusiasts love to get their money's worth out of the hardware they buy is to mod it. Whether it's flashing the firmware with a hacked version to unlock hidden features, soldering resistors across two connections, using modchips to bypass security checks or many others, it's always cool to learn about how to make your hardware go that extra mile. There is a great article up that talks about taking a plane jane shelf-bought $60 router and turning it into a routing powerhouse, with all the features and richness you'd expected from a business class device ten times the cost. A Linksys WRT54GL wireless router was chosen for the task, one of the most common home routers.
Of course, this relies on Linux. Given the amount of flexibility available to you in the various routing packages for Linux, it's no surprise that they were able to make that WRT54G do things like QoS and traffic prioritization, output power alteration for the wireless card and more, as well as the host of other features such as VPN functionality that the packages can come with. It's definitely an interesting read, and a great way to try some more advanced networking functionality without having to sink excess cash into it.