Couldn't resist the appalling title. Sorry.
This is the best egg timer I've ever used. Okay the alternatives (hourglass, watch, guesstimate) do much the same thing but these bad boys allow you to cook soft, medium and hard boiled eggs, regardless of how fast the water is boiling, regardless of the size of the pan or even how many eggs you're cooking at once.
Sure you need to keep an occasional eye on the pan and yes, they do melt if the water boils dry, but even so, they're worth every penny if (like me) you despise dunking soldiers into hard eggs. I've had one for years and used it loads, and everyone who sees me using it wants one - a nice Christmas stocking filler m'thinks!