I knew one of these days I was going to do it... Sure enough, this morning I did it: I forgot to hold back some of my starter.
Last night, as usual, I pulled my starter out of the refrigerator, fed it, and left it out in a cupboard overnight. This morning I put together a batch of dough and dumped all of my starter into the bowl. About five minutes later I realized what I had done and thought "Doh!" Or, perhaps because I was baking, it was "Dough!" I exclaimed.
Anyway, I dug through my baking books and it looks hope is not lost. Even though my dough had some olive oil, honey, and salt in it, I took a fistful out of the batch of bread I was baking, fed it another cup of flour and cup of water, and set it aside. I am seeing signs of life, and aside from a slight olive oil smell it seems like my starter will live to bake another batch of bread.