Low power customizable NAS?

[Kurt Granroth]

I'm looking for a NAS that looks roughly like so:

o Very low power usage (~10 watts or less, ideally)
o Can run squid or similar proxy
o Can serve up files like you'd expect as NAS to do
o Can stream media
o Can run Linux or, at least, is customizable

Anybody using anything like this already?

I'm not opposed to rolling my own with mini-itx or the like but I'd
prefer not to.  I do wonder if the proxy requirement is more of a
deal-breaker since most NAS units try to stay strictly in the storage realm.

One thought is adapting a Pogoplug or Seagate Dockstar or the like.  I'm
not yet sure if that'll do all I want, though.

Any thoughts?
Kurt