I emptied all the litterbox collection sacks that I had in the back room where the litterbox is. The past few times I've sifted/dumped the litterbox, I've put it in a black trash bag, and then just sat it down by the litterbox, thinking "I'll get to it later."
Yeah, whatever. I had about six "get-to-it-laters" sitting in there, and I finally decided I was officially Sick Of It.
So, I hauled them all out to the trash barrel. Took me about five trips, and I gave myself a mini-asthma attack and a bit of a back spasm, but it's done and I feel better about it. Now, unless the cats knock something out of the litterbox, that room is a high two...but at least it is no longer a three.