Vinegar and water for regular cleanings and when you do a deep cleaning use peroxide or alcohol (or some use bleach water) and make sure you let it dry completely and if you use peroxide or bleach, let it dry in the sun to oxidize the chemical away.
However, I recently got job at a pet store and we are suppose to use Buckeye Watchdog. It is really a great disinfectant, been told it is used primarily in the animal industry so I can only assume it's pet safe. But someone please correct me if I am wrong.