I noticed the other day that characters with a combat speed less than 1.0 in tactical combat never actually get to do anything. Except maybe defend themselves when attacked. Additionally, if the character has some extra speed from some sort of bonus, it is wasted unless you can get the bonus up to the next integral number.
So, I was thinking, why not let fractional action points carry over to the next turn? That way, a character with a speed of 0.5 will get to move or attack every other turn. And, if you have a speed of 1.5, then you get an extra attack every other turn. For instance.