Grapefruit Seed Extract (GSE) is a must-have in our home. It's strong anti-bacterial properties make it very useful for a number of needs. When I discovered GSE, I stopped depending on antibiotics to get over Strep. Gargling with GSE and water will kill strep infection in the throat. Of course, it tastes awful so I prefer GSE capsules for all other applications.
You can find a comprehensive list of all the uses and benefits of GSE here.