If you’re in the market for a low cost embedded Linux development board then look no further than the Omnima embedded controller. £23 gets you a MIPS platform with Ethernet and USB host ports, 16MB of RAM and (via OpenWRT) a wide-ranging repository of pre-packaged Linux applications and libraries. Compared to the likes of the Arduino, this is a lot of bang for your buck.
One of the convenient features of the eCos real time operating system is the ability to develop and test code on your Linux development PC without downloading to target hardware. This can be done using hardware emulation (via QEMU or VMWare) or just using the built in “Synthetic Target” support. I have documented here the various steps required to install and configure the Synthetic Target on Linux (Ubuntu). As well as supporting basic eCos threading you can even run networking applications in this environment via the bundled synthetic Ethernet driver.