Site Penalty

* Your site really does need unique content

* Sites can be penalised for particular keywords, typically if the site has a identifiable manufactured or worse, paid for, link profile

* Your entire site can be removed from Google if it contravenes Google webmaster guidelines

* Typically this is because your site has been hacked and links to malicious software injected into old code and scripts (watch contact forms)

* If your site is removed, you need to clean it all up and issue a re inclusion request in Webmaster Tools

* Be careful getting sitewide links from most sites - IMO take a couple of links from strong pages on the site instead with varied anchor text