Linux SBC recommendations

["Greg Lee" <greg@gregandsarah.org>]

I'm in the process of selecting a single-board computer (SBC) for a
project and I'd like to hear what others are using sucessfully.  My
requirements for the SBC are:

1) Low cost (<$100)
2) Runs Linux
3) Has an Ethernet and USB host connection
4) Has sufficient storage capacity to run an small HTTP server such as
mini httpd and a few MB left over for custom applications
5) Mechanical packaging suitable for a server room environment
6) Processing capacity requirement is not very large, low-power processor okay

I previously assumed that I would use the Gumstix Vertex-Pro boards,
but cost is a limiting factor on this project and precludes using
these boards.

What low-cost SBCs has the Linux Embedded community used with success?

Greg