I've got a Dell T410 I bought second hand. I've got 6x1TB WD Black SATA drives attached to a PERC5 in RAID 6. It's got 48GB of RAM and dual Xeon E5504s. It's running Hyper-V 2012R2, and hosts my MS home lab for testing, licensed through the now defunct Technet program. The MS lab is all 2012R2 and consists of an Exchange 2013 server, 2 DCs, and a CA. I use this mostly for testing stuff I'm going to do at work, as well as learning Windows garbage I wouldn't normally get to.
I've also got 8 Linux VMs running on it. 6 are running Ubuntu 14.04, one is running Debian Wheezy and one is running Debian Sid. The 6 Ubuntu boxes run my internet based PVR so that I don't have to deal with building a proper PVR to record my totally current active cable service; internet based Blu-Ray ripper so that I don't have to actually rip the discs I buy all the time; Plex Media Server to connect the aforementioned backups to my Chromecast/mobile devices/whatever; SABNzb to actually perform the backups; a custom WordPress installation running SupportPress so that my wife and roommate can submit tickets to remind me to fix the Roomba; a BitTorrent Sync box so that I don't need to deal with Dropbox. The Wheezy box is a Sendmail server for sending mail and the Sid box is one that I use to mess around with and test Linux compatibility with some Python stuff I have.
I've got a file server which has been running OpenIndiana, but I had to move that back to Ubuntu because OI doesn't currently support my motherboard. It's got an 80GB Intel 520 SSD as the OS drive, and a janky ZFS setup which works well enough for home use. The zpools are setup across 3 RAIDZ pools, each cnsists of a 4x1TB, 4x2TB or 4x3TB RAIDZ array. Each array also has a 20GB slice of a 120GB Vertex 3 as cache drives, with the last slice going to the smallest zpool as a slog. The smallest zpool gets the slog since it's running dedup as it houses backups for the Hyper-V box, my desktop and laptop and my wife and roommate's computers. It's got an i3 and 32GB of ECC RAM.
I'm currently in the process of waiting for a server to configure off-site replication of all my important/irreplaceable data to a hosted server through So You Start, formerly OVH. $42 a month for 2TB of off-site storage seems like a pretty great deal to me. It'll be running FreeBSD I suppose, since they don't offer Solaris.