To pick up on Jeffrey's ideas...
DH and I just changed to a new cell plan. Our monthly costs will go own about $25, we both got free phones and each phone came with a rebate!
Health insurance has also been a big expense for us, as we have to buy our own coverage. We've been able to change plans this year and are paying about $130 less per month now, if you can believe it.
I also agree with the eat-at-home tip. This is a big money saver for us.
I shop consignment and thrift stores, as well as eBay, for casual clothes for me and my daughter. I also resell on eBay from time to time. It doesn't reap huge rewards, but it's nice to get $1.50-$2.00 back on something that may have cost at most $5.00 to begin with.
When DD was still in diapers I switched from disposables to cloth. A year and a half of that saved us some money, even with the initial investment in diapers.