I have been using neem oil to ward off aphids and white fly from my beautiful chilly plants. The only thing I don't feel good about is that you can accidentally kill spiders and other good bugs when spraying neem oil, if they come in the line of fire :(
I accidentally sprayed a cute little spider yesterday who was trying to help me by catching those pesky white flies.
RE: Neem Oil - A Must-Have For Every Organic Gardener