A clone of the PDP-8 computer, the face plate and switches are available as a kit from "Obsolesence guaranteed" website, it's an expensive kit at just over £100 (Raspberry Pi not included) with lots of tinkering longevity, avoid if you don't like soldering and a good few hours work, but the end result will give you a thing of retro beauty.
A simple ISO image from ISS-Above, which you copy to an SD card, put in your Pi, connect to a monitor or TV for an out of this world live feed from the International space station, watching the sunrise it truly magnificent.
Limitless internet radio stations to listen to whatever your taste in music. I found "volumino" to be a great choice to write to an SD card, you will need some sort of Pi add-on to connect to speaker/s such as a Pirimoni speaker hat or for more power a Hi-Fi Berry amp, a nice simple interface, set your board type and wireless settings from your PC, phone or tablet, then lay back and enjoy a bit of Zen radio, bliss!
The amount of games available for the Retro Pi image is staggering, I have a 32gb SD card almost full! Add different rom's once you have set up the main Retro Pi image for a trip back in time to Sonic the hedgehog or a classic ZX Spectrum game.
The latest Raspbian pixel image is perfectly usable for an every day computer now, the early Pi's were slow but the Pi 3 with Raspbian is a lot more polished, decent learning software by default and Minecraft is always great fun.