Ordered lists of where to advertise. Each one says what its order means — a measure the directory computed, or a basis somebody chose. The computed ones are also on rankings.
The places a product gets listed on the day it ships.
Where a launch gets covered, and what a spot on them costs.
Publishers that sell their own handles, not just their pages.
Inboxes with a rate card.
The trade press the buyers themselves read.
Publications and communities that reach people who write code.