The expired domain that caught my eye today was KidandFamily.com, which I think you should definitely buy and develop if you’re a stay at home mom, or really any kind of parent that also has an interest in writing, because there are so, SO many different topics of interest within this field. You could talk about daycare centers in your area, schools, family-friendly events, restaurants, or any topic that you were feeling strongly about. If you got locally-specific traffic, you could definitely get advertising from local businesses in your area, because your demographic would be exactly what they are looking for.
So, go get KidandFamily.com now. Those opinions and resources you’re accruing over the course of each day will be useful to others, AND you can use them to make some money!