Matt was telling me about the Martian NetDrive Wireless, which is a pnp wifi file server. At $400 t looks pretty reasonably priced, made out of mini-itx parts (looks like a Morex case).
While looking on mini-itx.com’s hardware page, I spotted Traverse Technology’s MicroServer systems, which look pretty cool (but alas, no room for a serial lcd display). Bang per buck, I’d say the Hacom OpenBricks probably beat either of those out though. (and for overall cool/useful factor, the soekris units win hands down.