Just for fun, I fancy seeing what sort of rule other gamers fancy adding to Warhammer.
I'm going to cheat straight off the bat. and offer up two.
1. Firepower Pushback. It exists in WotR, and also in Warmaster (and possibly Warhammer Ancient Battles, but I've never played that). For those unfamiliar with it, essentially when a unit inflicts heavy casualties with bow, shot or what have you, the target unit is forced back a bit. Exact mechanic would need a little tinkering here and there granted, but it would offer an interesting new dimension to the game!
2. Breakthrough. Applies solely to Cavalry and Monstrous Cavalry. When charging, you have a chance of punching straight through the enemy unit should it refuse to flee. Again, would need a lot of tinkering, but here's my initial take.... If the number of casualties inflicted exceeds the defending units rank bonus, then the Cavalry breakthrough their ranks, appearing on the other side, provided there is enough room to do so.
Breakthrough appeals to me as it forces infantry heavy armies to put real thought into their deployment, as a single weakspot can be smashed aside by a concerted Cavalry attack, allowing the cavalry free reign behind enemy lines to do what they do best. Alo, it goes some way to giving Cavlary a bit more punch, without swinging the pendulum too heavily in their favour (remember, it's wounds cause, NOT basic combat Res) It would of course need some kind of limitation, perhaps allowing it only against infantry (Monstrous Infantry I can imagine being big and tough enough to absorb the charge)
So, let me know what you think, and don't forget to add your own rules! (army specific ones apply!)