Simply mix together 3 parts baking soda, and one part Dr. Bronner's or other Castile soap.
There are many "recipes" out there that include vinegar. While I am a BIG fan of cleaning with vinegar, NEVER mix vinegar with Castile soap. It unsaponifies the soap, separating it and making it useless. Oily and useless.
Now that you've got your scrub, you can clean all over the place.
Coffee spill under the maker and dry on the counter?
A little soft scrub with a rag: