Thermal Foundation:

• Phyto-Gro (Slag + Saltpepper)
• Rich Phyto-Gro (Phyto-Gro + Rich Slag)
• Bitumen (Sand + Coal?)
• Coal Coke (Coal + Lava?)
• Sawdust (Log + ?)

Hard to include and therefore not planned: Pulped Biomass/Bioblend
Thought about but not plannet: Destabilized/Energized/Resonant Clathrate (can use redstone/glowstone/ender pearl to get the same materials), Rosin/Tar (no real uses besides smelting and a few recipes), Fluxed Phyto-Gro (you'll need to energize it yourself)

Ice and Fire:

• Desert Myrmex Resin (Slime + Orange)
• Jungle Myrmex Resin (Slime + Cactus Green)
• Pixie Dust (? + ?)

Maybe: Shiny Scales, Stymphalian Feathers, Amphihtere Feathers (need to think of a recipe first as well)

Tinker's Construct:

• Aluminum Brass (Copper + Aluminum), need a check if those chickens exist

Maybe: Sliky Jewel (Emerald + Gold)

Extra Utilities 2:

• Enchanted Ingot (add nuggets to the mod and make chickens drop them) (Gold + Lapis)

Thaumcraft? (Quicksilver, Thaumium, Void Metal, Void Seed, Primordial Pearl?)
I'm not sure about it as they (or at least most of them) are somewhat harder and expensive to obtain.