Nega-Gamma Gun - A high-powered firearm that releases blasts of concentrated gamma radiation. Richards designed this weapon in the hopes of possibly curing the Hulk. (Incredible Hulk #153)
Shrinking Gas - Mister Fantastic recreated Henry Pym's Shrinking Gas formula in Fantastic Four #7. According to Marvel Saga #5, Reed Richards is "the only other scientist whom Ant-Man has entrusted with the secret of his reducing formula."
Awesome Android - The Mad Thinker developed the Awesome Android based on Mister Fantastic's research in the areas of DNA and artificial lifeforms.
Failed Attempts to Cure the Thing
Fantastic Four #8 - Developed a chemical potion that temporarily reverted the Thing to Ben Grimm. The effects wore off in a few minutes when the potion evaporated off of his skin.
Fantastic Four #11 - Developed a second generation chemical potion that temporarily reverted the Thing to Ben Grimm. The effects wore off after several minutes.
Fantastic Four #16 - Developed a third generation potion that temporarily reverted the Thing to Ben Grimm after being ingested. The effects wore off after several minutes (It lasted long enough to travel from Alicia's appartment to the Baxter Building). This formula was recreated and used as part of the Fantastic Four's plan to defeat Doctor Doom in Fantastic Four #17.