Surfing the web about this, I found it could be great to build a mini linux system using
- VIA EPIA CL Mainboard miniITX with 2 RJ-45 LAN port (17cm x 17cm card)
- one WIFI PCI card
- one IDE flashcard drive as the booting device
- some memory
- a case and a power supply.
Maybe overkill for such usage...