Mmmmm....fresh bread when you wake up.
I'm still amazed how much use we get from our bread maker, and that it wasn't just another kitchen appliance we've accumulated and never use.
I think what makes it so useful is the ratio of effort to results that it has. Add in a boxed mix that takes about 4 minutes to prepare (and almost not untensiles), set the timer for 14 hours, and poof, you've got the smell of fresh bread the next morning.
Our favorite recipies include Challah and pizza dough. The pizza dough is fun for company as you can have your guests add toppings to their own pizza before cooking and serving it.
It also helps that cleanup is a breeze.
I bet there are some lessons in here for designing any product people will use. Though I'll leave it to you to discover them. Me, I've got bread to eat.