Actually, I DO find my butter bell a necessity -- for me. I hate hard, cold butter on toast, English muffins, rolls, and baked potatoes!
Bought mine from Amazon, around $20, in yellow (Like butter, get it?!)
To use you put about 1/2 inch fresh water in the "bowl" part -- change it every 2-3 days for best results -- press your softened butter into the "bell" section (I use the paper the quarter was wrapped in to press it down), and place the bell into the water.
Why in water?? Because having the bell in the water creates an anaerobic environment for the butter which then does not go rancid. The butter doesn't get wet from the water as the placement creates a bit of a vacuum when you put the bell down into the bowl.
I LOVE mine and gave them for Christmas a couple years ago!
Jan in VA