Mini-ITX is cool
Here is my latest little project:
http://freak.purearea.net/stuff/cube.jpg
(no laughs about the case, i know i suck at building cases

)
As some here know i am very much into silent PC stuff (as evident by my addiction to watercooling)
and with this one i took it to the extreme:
- passively cooled itx board
- small power supply without a fan (it does not need an external notebook powersupply as with most such projects)
- flash Disc-On-Module instead of a harddrive (
http://www.dsl-ltd.co.uk/products/domspec.htm)
In total, there is not a single moving thing in the whole case (except the speaker)
... absolute silence
The basic concept is very similar to this project:
http://www.mini-itx.com/projects/rundfunker/
except mine is primarily aimed at playing webradio through the wireless network.
(it does play mp3 as well of course)
It is running DamnSmallLinux with anything that is not needed disabled to cut down
on the bootup time. The menu and lcd display stuff is of course written in PB.
For the development i am running xubuntu from a separate HD.
As for cutting down power usage, using a notebook HD helps alot. Even better
are these flash modules, although they are still quite small, and have a limited
amount of write operations before they get damaged, so they are not the
best for every kind of use.
Of course if you use it for stuff like playing DVDs, you will have a lot of power usage
(for an itx system). and there is not much that can be done about it.
If you use an ITX case that comes with a power supply, be sure to check a bit
about the power supply thats in it. They are sometimes quite loud, and sometimes
provide much more power than needed, expecially for systems that are intended
for server tasks only. Power supplies of 75W or more are totally oversized for
such applications.
My system runs of a 25W supply, and that is more than enough for what it does.