YES I am playing the PC version
It seems that there are standard icons for some thigns and unique ones for special areas. After more exploring I've found:
Wind Mill: A farm
Lopsided coffin: standing stones of different types that affect what equipable Powers you are currently using
Mammoth Skull: Where Giants and Mammoths camp
Big Ol' Bear Claw: A secret camp needed for a quest you're sure to find
Crossed Pick & Hammer: Don't be liek me and keep thinking they are spots to mine for minerals in WOW. It's just a general discovered location you've already found
To clear a custom target on your map: left click well away from the custom locationa and choose how you want to afect it.