TBO, here's what I do, as well as a link from mercola.com with other testimonials and info. I know I'm getting sick when I feel a headache coming on. Sometimes one of my ears will also "tick". Immediately put about 10 drops of 3% peroxide in one ear canal (lay on your side so it stays in the canal and doesn't leak out). Leave it in for about 10 minutes, or until the fizzing stops. If you've got germs in your ear canal it will fizz like soda! When that canal's done fizzing, flip over, drain the canal, and do the same to the other one. Usually after that I am very tired, and I go to sleep quickly. Then, just like magic, I wake up with no cold symptoms! Sometimes the peroxide treatment will work within minutes and my headache (or scratchy throat, whatever) disappears.
As long as your ear drum is not perforated or has a hole in it, I definitely recommend you try it next time you feel a cold or flu coming on. It must be done immediately though. Don't wait until you have a full blown cold.