Next to things like rent/mortgage...
And do you feel like you could pare it down?
Our biggest is food and daycare. I've consistently tried to cut our grocery bills but it doesn't seem to work well. We do eat a lot of produce, protein, and whole grains, and not packaged or pre made food so I think that contributes to higher cost, but we do buy in bulk to save (ie 25 lbs of oatmeal was $1 cheaper a lb).
Daycare, while a big spending category, is actually affordable for our area- and I doubt I could find anything cheaper, especially for the quality care we receive. I'm very pleased with the cost.
How about you?