When fleeing from an encounter (evasion rules as per Classic D&D), a character may discard their shield in order to automatically evade the pursuer.
No, I haven't playtested this yet. Yes, it could be powerful at low levels. Yes, it's unfair to those that don't use shields (but then the M-U's and Thieves are likely faster than the Clerics, Fighters and Demi-Humans anyway).
But if your group happens to run into a specter when you're only level 2, or your plan to surprise the sleeping dragon goes pear shaped, this will allow you to get away easily and live to fight another day.