Back-on-Track is a European network of volunteers campaigning for the expansion of better, more affordable night train services across Europe.
You can get a copy of their latest map here.
Their night train map highlights different operators and groups them by colour based on a colourblind-friendly palette. Individual services are noted in different shades of the operator's main colour, and even feature their website names!
Major connections are shown in rounded squares or circles, with a larger size indicating more connection opportunities. Each connection is labelled in a pleasant sans-serif font in their respective native languages. A romanized version of a destination's name is provided beside and inferior to the original non-Latin script (i.e. София/Sofia, Αθήνα/Athína).
Service frequency is delineated by line weight and style, with heavy solid lines indicating daily service while lighter dotted lines indicate weekly or seasonal service. Future services that are under development and planned to open later this year (ojalá) are shown as well. The lightest dots indicate seat-only connecting services, such as the connection between Lyon, France and Torino, Italy. The map even shows a handful of long-distance ferry services, such as those between Stockholm, Sweden and Helsinki, Finland.
The landmass of Europe and North Africa contrast well against a much darker ocean, with gaticules at the 30th, 45th, and 60th parallels for reference. Member states of the Interrail/Eurail program, an international rail pass available to European and non-European residents (respectively), are shown in a slightly lighter shade of blue than non-member states.
As a North American, I envy Europe. The fluid connectivity between to many countries to so many far-flung places across the continent is something I can only dream of. I can't even take the train to the country next door (Mexico) without transferring to a long-distance bus. Heck, I can't even visit San José from Los Angeles without taking a 10 hour train ride that meanders along the coast and through the mountains. One way. For US$124... This is why we fly.
Maybe one day we'll catch up. Ojalá.