Laptops and especially netbooks with broken screens also work great for this if you need a little more computing power and can double as HTPCs and Wi-Fi hotspots [1]. You can often get one for less than the price of a RasPi or free. Remove the upper lid completely to get a ZX Spectrum/C64 style keyboard computer [2] for easy on-the-spot administration. The built-in battery acts as a UPS, which is also nice.
The downside is that, unlike the Pi, they can make noise. Still, that can be remedied.
[1] If you can find wireless drivers that support host mode. No small feat under FreeBSD.
[2] Here's mine: http://imgur.com/u9i9fUx. It's an Asus Eee PC 1001PX. Currently out of commission because it got replaced by a self-built AMD E-350 Mini-ITX system with a PicoPSU.