- Vinegar - This is what I use most often. Run an empty cycle with about 1 cup of white vinegar in the bottom of the dishwasher.
- Citrus flavored unsweetened kool-aid - Dump a packet in the soap door or in the bottom of the dishwasher and run a cycle.
- Bleach & water solution - This is to use if you have a mold problem. The bleach will kill any mold growing.
Short and sweet but that should leave you with a clean appliance that will appreciate being maintained.