The install instructions for the eth Ruby gem is referenced below, but you will more-than-likely need to install other packages to get eth up and running:
Having installed and configured geth and the Ruby eth gem, synced the entire Ethereum blockchain, I'm honestly stuck on finding a real-world, useful, practical Ethereum distributed application to code, further developing skills in this area.
If anyone can provided a practical, simple, useful (and not difficult to code) Ethereum application, please reply with details.
Getting all the details of geth up and running flawlessly has been non-trivial so far; so I'm reluctant to put a lot more quality time into this caper unless I can sink my teeth into a practical, fun application to build.