There are a few mods that only require a certain material to start off in, so I suggest adding bees for them, or at least those items to existing bees:
Black Quartz Bee- Actually Additions
Osmium Bee - Mekanism

Besides that, I suggest completing:
The Tinker's Construct support by adding a Bee for every type of Slime.
The TechReborn support by adding Iridium