Laws about links

[RedMark]

Are there any laws about linking to other web sites? Is it necessary to get someone's permission before including a link to their site on my site? What's the courteous thing to do?

Comments? Suggestions? Opinions? Good-natured laughter?

[Dcrux]

This may be a good time to introduce the site Don't Link To Us (http://www.dontlink.com/). Many sites have what is called a linking policy.