As a base service for bare metal infrastructure I prefer my provisioning and configuration management servers to be bare metal which can be accessed without requiring other hosts or infrastructure. For small deployments the Raspberry Pi makes a great choice because it is inexpensive, uses little electricity, takes little space, and yet has enough power for the relatively low demands placed on the server (which also makes a full x64 server overkill).
For small deployments (or home or small office use) you may find yourself in need of a 'bare metal' server, but not want or need the expense of an x64 machine. If the workload is not too demanding, a Raspberry Pi can be a good choice. The Pi has the benefit of being inexpensive, using little electricity, and taking little space.
I've now built sites using a variety of static generation methods, participated in wikis and other's CMS systems, and was hosting a Plone instance (dynamic CMS), so I've decided to post a comparison of the different (and similar) trials and tribulations of using open source solutions for dynamic vs static web content management.
Around 2011 Android devices based on the WonderMedia 8xxx-series SoC (ARM v5) were being sold as netbooks. This article describes getting Debian 7 (Wheezy) running from SD card on one such: a Craig CLP281 Netbook.
Not worth it for most SOHO (Small Office Home Office) / startup deployments. I'd call three storage nodes, two controllers, and five reasonably beefy compute nodes the minimum to even consider the option. Headless libvirt combined with virt-manager makes a far less complicated VM environment and it can be online much more quickly.