A brief list of my home systems:
3.4 GHz Intel Core i7, 4 GiB RAM, Gigabyte H61M-S2P-B3 motherboard, 2 x WDC WD20EARX 2 TiB "green" drives (seriously, don't buy these for any kind of server) in a RAID1. Really great Antec case and PSU.
Usually runs the latest NetBSD release. Took over from zion running public ftp, http, smtp server.
2.8 GHz Pentium IV HT, 1 GiB RAM, Asus P4P800-E Deluxe motherboard. Antec Performance II SX1040BII case - best case I've ever worked with. 4 x 2 TiB WDC WD20EARX disks, two already dead, in a pair of RAID1's.
Running NetBSD-5.1-RC4 x86 + MP kernel.
Runs as a public ftp and http server. And runs internally as a MySQL server, PostgreSQL server, NFS server, NetBoot server, Squid cache, Samba server, Netatalk server, Wireless LAN router, NetBSD build box and backup server. Probably other stuff, too.
Little Dell Dimension C521, with AMD Athlon 64 dual-core 3800 (2 GHz), only 512 MiB RAM, and built in NVIDIA GeForce 6150 LE (unfortunately with no mode switching support in the 'nv' driver in xorg or XFree86).
Usually running the latest NetBSD amd64 release, but mainly runs Windows XP when I have to. Came installed with Vista (yuck!).
Old box was a 900 MHz Athlon, 1 GiB RAM, 1 x 20 GiB Seagate ST320423A disk for NetBSD and xen, 1 x 17 GiB Seagate ST317221A disk. After a power glitch that fried the motherboard, disk, CD drive, PCI sound card, PCI SCSI card and even a USB mouse (yes, the magic blue smoke escaped!), all but the case, fans and RAM is scrapped.
DEC Alpha Multia AXPpci233 233 MHz, 32 MiB RAM, 500 MiB SCSI disk.
Runs NetBSD-3.0 alpha netbooted or OpenVMS 7.2 on local disk.
Unfortunately, something is fried in the poor thing, it no longer powers on.
Sun SPARCserver 5, MB86904 110 MHz CPU, 64 MiB RAM, bunch of old SCSI disks (unplugged, too noisy!), running NetBSD-4.99.xx, netbooted off zion.
Apple Macintosh Quadra 605, 25 MHz 68040, 20 MiB RAM, Quantum Fireball 1080S 1 GiB SCSI disk, running NetBSD 4.99.xx. Yes, a 1993 vintage system running the latest and greatest NetBSD release, and running it quite well.
Apple Powerbook G3 'Wallstreet', 300 MHz PowerPC G3 (PowerPC 750), 320 MiB RAM, 8 GiB disk.
Ran Mac OS X 10.2.8, until the disk finally gave out after sounding really bad for a year or more.