This screencast introduces the hyphen an provides some examples of its use.
Source: Kathryn Reilly
Hyphens can be a tricky punctuation mark. The following websites offer many examples of when a hyphen is and is not necessary:
http://www.englishforums.com/English/RulesForUsingHyphens/gqxx/post.htm
http://www.grammarbook.com/punctuation/hyphens.asp
Source: see above