As an old Embedded guy who actually cares about resource usage, I've been bothered for quite a while by the number of trivial projects out there that require a full-blown MongoDB or MySQL server to operate. It's a particular problem on the Raspberry Pi or small DigitalOcean Droplets. In many cases a simple SQLite DB or TingoDB is more than sufficient. Here's some notes on using them.
ZeroMQ is a lightweight messaging library and looks ideal for lower powered devices like the RPi. Building and running is pretty easy. These are more notes for myself for future reference.
