there are other small desktops
We're using the eBox 3300 from DMP/ICOP out of Taiwan. WDL Systems in the US carries them. About $150 for a bare machine in quantity 1. These have a 1GHz Pentium equivalent processor with 256MB of RAM. They come with USB ports and a CF port and a micro-SD slot. The power supply is rated at a max of 10W, so they can't be pulling much more than the Linutop 2. I would not run a compute farm with them, but for most things they are just fine. Installing Linux is a little tricky as they use somewhat rare hardware for the IDE controller and the ethernet.
We're using them as embedded machines and they are working very well.