I got some raspberry pi 3s kicking around and would like to put them to use.
For your pi 3, just grab the ARMv7 binaries. https://getmonero.org/downloads/ They'll work for pi 2 as well. If anyone is trying to run a node on pi 1 or pi zero, I can upload ARMv6 binaries but I believe the plan is to drop support for these ARMv6 devices soon.
ARMv6 binaries now available: https://www.reddit.com/r/Monero/comments/543euo/monero_unofficial_arm_builds/
Also ARMv8 binaries for boxes running 64bit OS. This excludes raspberry pi 3, which only ships with a 32bit OS, and doesn't support ARMv8 crypto instructions.
Rasbian is out because its libboost-all-dev is only version 1.55 (1.58 is required to build). I don't have an rpi3 with Arch Linux on it to test on right now, but that would probably be your best bet since it is a rolling release distro.