Once upon a time, there was the original R Graph Gallery, by Romain François. Sadly, it’s been unavailable for several years. Now there’s a new R Graph Gallery to fill the void, created by Yan Holtz. It contains more than 200 data visualizations categorized by type, along with the R code that created them.
You can browse the gallery by types of chart (boxplots, maps, histograms, interactive charts, 3-D charts, etc), or search the chart descriptions. Once you’ve found a chart you like, you can admire it in the gallery (and interact with it, if possible), and also find the R code which you can adapt for your own use. Some entries even include mini-tutorials describing how the chart was made. You can even submit your own graph, if you’d like to have it displayed in the gallery as well.
Looks like a good place to go to get some inspiration.