My group has expanded on thrown rocks and javelins. We called these mods to rocks and javelins, but they’re basically launchers:
Atlatl: Adds +2 combat dice and +1 range to a javelin
Sling: Adds +2 combat dice, +1 range, and Inaccurate to a thrown rock
New perk: Primitive Hunter
At Rank 1, when using thrown weapons, gain +1 combat dice and Accurate (or remove Inaccurate). At Rank 2, add an additional combat dice and Piercing 1.