I don't keep many seasonal, single-use tools in my kitchen drawers; most pull their weight year-round. But I make an exception for this cherry pitter, which, to be fair, isn't entirely single-use: it does a great job on olives, too.
It's the first cherry pitter I ever bought, and it's still going strong today, several years later. It's strongly, handsomely constructed, with a smart shield that protects you from that little squirt of juice that pops out of the juiciest cherries and olives.
This pitter makes it actually fun to punch holes in a couple pounds of sweet dark cherries. The reviews across the web (on Amazon, at Williams-Sonoma) largely agree with my take; one reviewer calls this an "unexpectedly delightful" cherry pitter.
It works well for both cherries and olives, and its guard shields you from most of the cherry splatters. But not all, of course — where's the fun in that?