Out of the ~40 items in the devil room, there are 7 that immediately grant hearts when you pick them up.
This mod add the number of hearts granted to the lower-left of the item icon.

This mod basically exists because I prefer not to check the wiki while playing, and this helps me make more informed devil deal decisions on the fly.

The items affected:
The Mark
The Pact
The Nail
Ceremonial Robes
Abaddon
Missing Page 2
Satanic Bible (technically not on pickup)

Big thanks to the http://platinumgod.co.uk/rebirth site for making checking everything so simple.