The Notched Pickaxe
The Notched Pickaxe is most likely a reference to the game minecraft, in which players can use pickaxes to mine ore. The creator of minecraft is also called Notch. And last, it ups your smithing by 5 points, smithing being like crafting, but in skyrim.
Choose your own adventure
The book "Kolb and the dragon," is like a choose your own adventure book.
300
If you head just south of the Shrine to Peryite, only small journey west of Karthwasten, North-North East of the Lover Stone, you will come across a skeleton (about halfway up the mountain). If you look just to the side of the skeleton you will see a sabre cat stuck between two rocks with a glass sword through its mouth and head. This is a reference to the scene in 300 where Leonidas leads a wolf to a narrow passage then stabs it through the mouth with a spear.