For those who want to get some simple and elegant icons that you can use both in your visual maps and as inspiration for your hand drawn maps, The Noun Project could be the solution.
As it's written on the Web Page, "The Noun Project collects, organizes and adds to the highly recognizable
symbols that form the world's visual language, so we may share them in a
fun and meaningful way".
You can browse various icons collections, one of my favorite's one is The Maki Map Collection.
If you want to customize the icons, it's very easy using a free software like Photofiltre.