Small items in a dishwasher such as cup lids and baby bottle tops often end up falling to the bottom or filling up with water. Keep them in place and easy to access by placing them in a small mesh laundry bag.
Those bags are normally designed for "delicates", but as the Real Simple weblog points out, they can also help keep small items together and get them washed more effectively. A simple but effective tip.
Laundry Bag as Dishwashing Aid [Real Simple