I've been a huge fan of singleboard computers for a long time. I've played around with several different once, but I must admit, the community which the RPi brings with it is hard to beat!
Some of my favorite projects made for the pi would be:
- Pi-hole - A DNS that will remove ads on your LAN.
- RetroPie - All the retro gaming you could wish for.
- Kali - Well, Kali on a RPi. That is just so super cool an convenient in a lot of cases.
- Kodi - An amazing open-source media center.