Electric kettle. I am partial to this one. It has a nicely designed base where it will sit on it with the handle pointing in any direction.

It's easily the most-used small appliance in our kitchen. We use it every morning for coffee, all the time for tea, oatmeal / hot cereal, boiling up water if you want to get crud off of a pan, whatever. You can even cook eggs in it (carefully; you put the raw eggs in and hit the button, it goes up to boil and then shuts off, and you let the eggs sit there for a few more minutes -- easy).

Due to the low US voltage it's not as fast to boil water as Euro 220V kettles but it's still amazingly convenient.