Since theres currently tons of events to invoke misery on the player, but relatively few to help the player, here are a few positive event ideas.
Shipping error : Another colony messed up on the coordinates for their metal / food / gun shipment, and it lands in your base for you to take.
"Lucky" thunder strike : A bolt of lightning hits JUST right, and gives your grid a large jump of power.
Bounty hunters : A group of bounty hunters just so happened to be commissioned to take down the group of raiders attacking you due to attacking another base previously, so you get assistance for the battle.