This Dagstuhl workshop included a wonderful art exhibit, titled “Bending Reality: Where arc and science meet.” Exhibits included this image by David Eppstein, and also this one:
There were also several metro maps, including ones based on concentric circles and freeform Béziers, as well as some curved annotations of the world and images of curved relationships, like this poster:
See also this blog post, and my previous post about CIRCOS diagrams.