I built a fanless mini server, using recommendations found on this board.
These two threads especially :viewtopic.php?f=20&t=63763&p=553738&hilit=FC8#p553738viewtopic.php?f=28&t=62702
, but also other threads.
I ended up using these components :
Streacom FC8 fanless case
Intel DH61AG motherboard
Pentium G630 cpu (sandy bridge, dual core, 2.7GHz)
8GB corsair 1333 MHz (2 SO-DIMM kit)
Intel X25-m 80GB ssd
90W Fortron external psu.
The system is performing wonderfully, running server software on an ubuntu 12.04 install.
Plenty of cpu power, the cooling ribs on the case doesn't even get luke warm.
The Streacom FC8 is a bit tricky, be careful to read the user manual online, there is none in the packaging. And there are many things to get right, before starting.
The rest was easy as cake. If you're buying all items from scratch, consider mSata SSD. The DH61AG supports it. I had the Intel SSD lying around to use.