Boon Ideas:

• Item rewards (Diamonds, cloth, etc)
• #111
• Attribute boosted (speed, haste, jump, luck etc)

Bane Ideas:

• Attribute cut (speed, haste, jump, luck etc)
• Eye sight cut
• Inability to read player names
• Shuffle items in chests that players open

The Cosmere RPG could give more ideas for specific boons and banes once the Stormlight module is out. Here's an excerpt from the Stonewalkers adventure that was shared in one of the Kickstarter updates :) I'll see if I can share the rest once it comes out fully in Q2