I haven't been using it in my pbp game, but Makofan uses it in his pbp game here -- and it saved Gallaine when she was a 1st level fighter! Given that and some recent face to face gaming experience, I'll probably introduce it into my pbp game early next year.
With this houserule, you get the usual -1 to your AC with a shield. However, any time you take damage, you can opt instead to say your shield absorbed the force of the blow. The shield is shattered and must be discarded, but you don't take any damage from that hit. It's quick, it's easy, and it's valuable.
On a 1 I will place a tic next to that melee weapon, three ticks and the weapon is broken, magic weapons will be handled differently. Repair cost is 1/4 of the item's cost in the book, not what you may have bought it for.
Bows are going to be a bit different, on a 1 you have snapped the bowstring and I will roll again if it is another one, you actually have damaged the bow not the string. ((Still thinking about what a bowstring might cost, if anyone would like to chime in on this one I will take suggestions!))
Crossbows will be handled as melee weapons at this time...
Thanks to the Society of the Torch, Rope and Pole for this one!
IF you roll a natural 20 while making some type of "skill" check you can describe or ask for something "cool" to have happened. An example was a Natural 20 on a "acrobatics" check, the player asked if he could shoot his bow, I allowed him to go ahead and make an attack roll! He hit and killed his opponent and landed in a flourish. Very Cool.