I, too, use ether. Some people think that ether "suffocates" a chick but it doesn't. It is an anesthetic and works just like being "put to sleep" for surgery. You can even heavily spray a folded paper towel and hold the chick in your lap on top of the papertowel with something light overtop...like a washrag or dishtowel. Ether doesn't smell very good, but it causes unconciousness pretty quickly in the chick. Then, you can either snip off the chicks head (I can't do that...) or put it in a coffee can with the soaked papertowel and it will die in a few minutes from an overdose of the anesthetic.
Although it's sad...and difficult to do for some of us...I do believe it's the most humane thing to do.