What is any good medicine if not a home remedy with really good marketing?
I'm willing to bet that there are more effective treatments for various illnesses than what is currently available on the market simply for lack of marketing. I am a big fan of trying things that "my grandfather has done for years" and I find that most home remedies lack both expense and most harmful side effects which is nice.
What are your home remedies?
For Pink Eye (and other eye irritations): black tea. Just brew tea like normal and then, when warm (not hot), dip a cotton ball in the tea and wipe away and gunk. Not a bad idea to let a little tea pool in the corner of the eye and let it sit. It feel soothing too.
For diarrhea: Peppercorns. Three or four peppercorns - swallow them with a glass of water.
Insomnia: chamomile tea