OK, OK, I know that technically the Zero W is a member of the Raspberry Pi family, but this one is too awesome to not list!
Because for only $10 it offers a very impressive feature set:
The NanoPi NEO Plus2 is less than half the size of the Raspberry Pi, but it packs a performance and storage punch
All that for $25.
A coin-sized Linux computer that is totally open-source, and costs $20. This is a small, low-cost, totally open-source (both the hardware and software) computer that's ideal for projects such as IoT or building your own custom router.
The Huawei HiKey 960 is essentially a PC running Android.
At a whopping $239 it's not cheap, but it certainly has the horsepower to handle whatever task you want to throw at it.
At $9, C.H.I.P. is a perfect demonstration of how cheap computing has become. You get what would only a few years ago have been desktop power on a tiny board.
ODROID-XU4 is a new generation of computing device with more powerful, more energy-efficient hardware and a smaller form factor, and costing only $59.
Offering open source support, the board can run various flavors of Linux, including the latest Ubuntu 16.04 and Android 4.4 KitKat, 5.0 Lollipop and 7.1 Nougat.
Not only does the Cubieboard4 pack a punch, it can output 4K video, making it a great choice for those wanting to build a media center or a gaming platform.
At $160, this board doesn't come cheap, but it's a solid basis on which to build a project on.
The Parallella computer is a high performance, credit card sized computer based on the Epiphany multi-core chips from Adapteva. Starting at $99, the Parallella can be used as a standalone computer, an embedded device or as a component in a scaled out parallel server cluster.
While the BBC micro:bit is primarily aimed at schools, its low price (about $16) and ease of use makes it a great tool for learning and prototyping on.
The micro:bit is powered by a 32-bit ARM Cortex processor and comes with a built-in accelerometer, magnetometer and Bluetooth.
A unique feature of the micro:bit is the integrated 5x5 LED matrix that offers 25 individually programmable red LEDs to use as a basic display or output.
The NanoPC-T3 is the bigger brother of the NanoPi 2 Fire, and features an octa-core processor which has enough power for commercial and industrial applications.
A cheap, $23 quad-core powered board that's ideally suited for hobbyists.
The MinnowBoard MAX is an update of the popular MinnowBoard, and features a 64-bit Intel Atom E3800 processor, 2GB of RAM, and Intel HD Graphics.
There's also a SATA port allowing the MinnowBoard MAX to be hooked up to a hard drive.
At $139 it's not a cheap board, but it does offer a number of high-end features.