Some neat resources useful to scientists that I have come across:
Phylopic - https://www.phylopic.org/ - "Free silhouette images of animals, plants, and other life forms, available for reuse under Creative Commons licenses."
R Colour Palette Finder - https://r-graph-gallery.com/color-palette-finder - "This page is an interactive tool for efficiently exploring all those palettes. In an instant, you can see a palette applied to various charts, find your favorite, and effortlessly obtain the corresponding code snippet."
Natural Earth - https://www.naturalearthdata.com/ - "Free vector and raster map data at 1:10m, 1:50m, and 1:110m scales."