I've made the whole roasted snapper basquaise from the Les Halles cookbook a few times now, and I usually just baggie whatever fish parts are left on the platter and hurl them into the back of the freezer. Now that we've got Trader Joes, I'm buying more frozen food in general, so I had to make room. I almost just gave up and tossed my scary looking fish-bone-cicles (there were some ancient shrimp-shell snowballs, too), but instead I sautéed whatever ersatz mirepoix was in the bottom of the fridge and threw it all in a pot of water on the stove, straining the resulting stock six hours later and throwing the now more stackable containers back in the freezer, not sure whether it was worth the bother.
Well, I thawed those suckers out today, and added some Trader Joe gnocci, frozen seafood and frozen balsamic roasted vegetables. The results: awesome. Literally one of the best things I've ever cooked. So yes, fish stock is worth a little bother. Also, we need a bigger freezer.