Here is another suggestion i have but its more aiming to the stats when you level up:
Lucky Ore: Each level in this stat will incese the chance of ores instead of stone by 1.5%
Lucky Vine: Each level in this stat will earn you 0.5% chance of twice the yield in an ore vine (Basicly it loses 5% instead of 10% on every hit)
Quick Learner: Each level in this stat will incese your experience earned by 1-5?%
Loot Goblin: Each level in this stat will give you a 2% chance of more loot when opening the secret chest.
Wood Cutter: Each level in this stat will give you a 1.5% chance of a rare log when chopping tree's (uncommon or rare)
Wood Expert: Each level in this stat gives you a 0.5% chance of earning more wood then usual (+1-3)
Carbon Troll: This stat will incese the chance by 1.5% of carbon instead of coal/stone.
Coal Miner: This stat will incese the chance by 1.5% of coal instead of carbon/stone.
If i come up with more ideas i might edit this one else i cant really think of more atm...