You better watch out, because the police are about. They scour your and pick out the most unspeakable crimes against HTML markup. This handy list of ten HTML tag crimes sheds some light on some of the most common coding mistakes and helps provide an alternate solution. Tips include writing valid markup, making semantic choices, avoiding deprecated tags and more!

http://line25.com/articles/10-html-tag-crimes-you-really-shouldnt-commit