Hello,

I have a project that requires a physically very small PC/Server to run a basic Linux distribution. I have searched the internet and the smallest I have found is this:
Stealth Little PC LPC-100

I am really looking for something smaller (like pocket sized). The only components it needs are:
-SD Card Reader or other small interface for Filesystem storage (could be SATA).
-One USB Header (2 USB ports).
-One Ethernet Network Port.

No Video Output, Audio Output, or anything else is required. Really, just USB is required.

Anyone have any ideas where I can find hardware like this?

I don't think you can get any smaller than the Gumstix line of single board computers. They have a number of models available, but they all feature microSD and USB. You will need to get an expansion board to get Ethernet, but the cost is still pretty low.

The Sheeva Plug may fit your requirements, too. You'll have to google for it. I picked one up for $99 +shipping.

Bigger than a Gumstix, smaller than a breadbox.

Sheeva Plug looks good!

This would be to much I think, but it's nice and small.