My main server is a Cyrix P166+ with perhaps 64 MB of RAM (that number is subject to correction, the next time I think to ask) and a few gig of disk, running Debian Linux. It lives in Seattle.
The imageserver, oriel.bazilians.org, is a Sparc 2 with 64 MB of RAM and 2.1 gig of SCSI drive, running NetBSD. It lives in Laurel, MD, on a pleasantly speedy connection to the Net. (It is my studied conclusion that if you think you need the latest, spiffiest machine to serve forth your Web pages, you should check to see whether you are connected via T-3 or better, or whether you are performing some sort of massive server-side processing, as for example lookups and updates in a nice fat database. If neither of these is the case, your "need" is likely to be fictitious. My Sparc, which cost me a whopping $20 [plus another $20 for its hard drive], can handily saturate a full T-1 connection.)