Another use for hydrogen peroxide is to treat bacterial vaginosis (bacterial infection of the vagina - very different from yeast).
It has actually been shown to be effective even *without* antibiotic treatment and even in cases that did not respond to the first round of treatment.
Better still, because it helps balance the pH of the vagina, it encourages the regrowth of "good" bacteria. Keeping things healthy down there is a delicate balance. Treating for yeast can encourage BV and treating for BV can encourage yeast! If you've been diagnosed, you might want to ask your doctor about this treatment.
The study I saw used the three percent concentration of hydrogen peroxide.