Wow! Learned something new today about mouthwash - which I never would have expected. Bee balm (wiki) is the natural source of the antiseptic thymol (wiki), the primary active ingredient in modern commercial mouthwash (wiki) formulas.
I was only looking for companion plants to help tomatoes, and then looked up Bee Balm and now not only can I plant it for helping tomatoes, I can plant it to help me, too - just look at all the uses! Oh yes, and it's pretty to grow and look at, too.