My store likes to try new things and this week we used the following rule for fun and testing: we all knew about the rule before arriving, so we had time to build our squads accordingly.
Rule: When shooting at a target and the line of fire passes through a friendly ship add 1 defensive die (Maximum) to the target.
We played a fun group game with this rule in play at my store. At first I didn't think I would like it, but after playing it really makes it a very different game and requires much more skill for maneuving which is a good thing. It makes turrets not as powerful and also helps balance out swarms.
Try it an see what you think?