Investing in a scratch map allows you to have a visualisation of all the different countries you've travelled to, as well as give inspiration to what countries you'd like to visit next. Scratch maps are extremely easy, but highlight effective. These world maps come in all different sizes, and look like any ordinary world map - but instead of being plain paper, it has a second layer of plain coloured foil added on top. The foil can be scratched away with a coin of finger nail to reveal a contrast colour underneath, highlighting that this particular country has been travelled to.
It's a simple idea but heaps of fun!