Keywords are important – no doubt.  Bit by bit Google and the other search engines are creating new ways to evaluate your site and direct searcher to quality results.  Sites that pack keywords in their titles, headings, and tags are coming under closer scrutiny.  If the site is also packed with ads and thin content, Google will penalize the site.  Thin content includes things like external links that have no relevancy to the presumed purpose of the page and content copied from other sites.  Google gives bonus points to original, helpful, and relevant content.  When linking to external sites it should be done in the context of providing more information for users wanting to explore the topic more after consuming your content.   A page with a list of plain links probably won’t impress Google much.  Google also loves videos and original images.  They imply a content rich site.  Remember –  Google owns YouTube.  Stay away from schemes to have your site listed on hundreds directories in order to boost your results on search engines.  If Google identifies those directories as link farms, your ranking will crash.  Stick to “white hat” techniques.  If you have quality and meaningful content for your target audience,  Google wants to find you.  Follow their guidelines and you will be rewarded.