Besides the Plugcomputers, there are other low power computers, also named as embedded computers. However, they are mainly aimed at industrial use or for developers and that they usually need an external power supply. Examples for such low power computers are:

The advantage of Plugcomputers is that they are usually delivered with an operating system (like Debian for the GuruPlug/Sheevaplug) and that they are popular enough that a community evolves. The community makes it much easier for development and if any problems occur.