Many homeowners protect their hardwood flooring with a polyurethane coating or some sort of shellac to give it a glossy or semi-glossy finish. If your flooring has a coating such as this, your cleaning will be even easier.
All your floor will need to keep it clean and looking great is a damp mop. It is important to remember that excess water is a hardwood floors worst enemy so make sure no water is left standing on the floor.
Your mop should only be slightly damp. If you do have spots or stains that are not removed with a mop, a cleaning rag with water or cleaning solvent for hardwood flooring website works great.
There are several different cleaning solutions that come in spray bottles for situations such as this. They're relatively inexpensive and last a long time because they are only used for those rare times when a mop doesn't get it all.