There has been a large increase in both the amount of plastic in the oceans and in public awareness of the issue. National Geographic and Nature have both done a good job of covering this issue. Cartographer John Nelson made a wonderful map, inspired by the rivers/mountains type of diagrams that I recently featured here, showing the three most contributing rivers in that style.
For better resolution click above - here is a detail from the Yangtze River.
I like how he managed to give this not only an old style look but also make the river colors and textures look a bit like plastic.  Also it is worth noting that the boxes on the bottom of each river represent the weight of about five cars, this weight is multiplied by the number of boxes EACH DAY.
For more on Nelson's map click here


National Geographic also recently published an excellent graphic story on this subject. Here are rivers with circled sized by level of contribution of plastics,
and here is a graphic view. This is just for Asia,
and here is the rest of the world.
Note that the scale on the two above images is close but not exact. To see these side by side scroll through the article.

Finally, a map of the Yangtze basin showing the sources of mismanaged municipal plastic waste.

Beautiful Trash is a pretty visualization of trash truck routes created using Tableau, a good example of creating maps with non-GIS software. A week's worth of GPS tracks from the City of Cincinnati are color coded by collection day.
The black background really makes the colors pop. The areas served by each day show up nicely. It appears that Friday is a kind of pick up the missed stuff day and has by far the most mileage. Hover over a route to see the truck number and coordinates. You can choose a day at the top to see in isolation - for example Wednesday.
Also when you choose your day a kind of summary route appears at the top which I don't quite understand.

Anyway kudos to Jeffrey Shaffer for turning trash into treasure.