The obvious rules, as written by Christian Buckner:

1. No pornography.

2. No pictures of illegal acts (drinking, drugs, downloading MP3's, etc.)

3. No excessive swearing.

4. No excessive vulgarity.

5. No attacks.

6. No tech abuse.

7. Upload your own photos, not someone else's. Copyrighted images are a no-no.

Behave yourselves or we'll tell the police or your mother, depending on which is more frightening.