Jacobs ladder, adds electric stun effect to tears for like 10 seconds?

mom's knife is also rad

Horf! pill could be an U-Smash similar to snake's mortar in Smash bros.

Godhead: gives tears a damaging aura. (no homing as that would just be ridiculous)

monstro's tooth: it summons monstro for a slam attack

maybe ball of tar rubber cement and sad bombs

Soy milk
Pros: Faster fire rate
Cons: Lower Damage Dealt

how to jump, simply make jump better when you have the item

brimstone would be really cool!

Doctor's Remote and Telepathy For Dummies, both being used over netural special.

Doctor's Remote: add a mark on the screen that can be controlled with movement keys and after 5 seconds (or earlier by pressing special again) it will send a explosive missile to the marked point.

Telepathy For Dummies: Makes isaac's tears have a bit more range and home in to players for 10 seconds.

Both of these could have a cooldown or have a charge bar that goes up the more damage you deal to players