For a little added pressure in the end game some groups use the following house-rule:

 "If a team makes a legal attack on the King and fails to topple it, their turn immediately ends and the opposing team is allowed a single legal attack at the King and an opportunity to win the game, regardless of how many Field Kubbs or Base Kubbs they have remaining."

FUN FACT: This "Variant" is apparently the standard in New Zealand, and as such we have heard this referred to as "Kiwi Rules"