LANshark offers a full-range of preconfigured and pre-installed Linux systems from $495 up to over $10,000 for use as workstations and servers. RAID and rackmounted systems are an available option as well. (Ohio-based.)
Vendor of some economical, and reportedly decent quality, cases, including rack mounts.
A project to manage ongoing development of the source code for the server management code for the (now discontinued by Sun) Cobalt Qube and RAQ servers.