Travel-themed nurseries are definitely more popular now than when we put together our travel nursery. The main reason I started talking about it here is because the only thing I could find years ago was a single forum post on a housing blog, and even that started diverging more into planes, trains and automobiles than truly travel themed.
And the only reason we hand painted our world map wall mural didn't use a simple wall decal like this giant one on Etsy was because I couldn't find any to buy back then. This one even comes in 31 different colors so it should work in almost an nursery color scheme.
Take it from a guy who spent three days painting a world map on a wall, do yourself a favor and just buy a decal. Not that I don't love our wall art, I just wish I had those three days back.