Here is a great article on Weblog Ethics.
1. Publish as fact only that which you believe to be true.
2. If material exists online, link to it when you reference it.
3. Publicly correct any misinformation.
4. Write each entry as if it could not be changed; add to, but do not rewrite or delete, any entry.
5. Disclose any conflict of interest.
6. Note questionable and biased sources.