Spyglass

Spyglass is a WAILA-inspired addon that displays information about the block/entity you are looking at.

It displays what mobs/blocks you are looking at. It displays what's inside chests -- after you open them. 

It has external addon support, displaying info about the new blocks and entities in the Add-On.

Images:

This addon is not complete. Expect bugs.

Turn on Beta APIs for this to work.