Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.
If you've been experimenting with the idea of writing device drivers for Linux, Free Software Magazine has written an extensive article on this topic. The article starts with the differences between kernel-space and user-space components and then ends with using LEDs connected to a parallel port as the device. This how-to guide can be read here.