Navigation:
The site navigation is from an architecture point of view the most important part of the site, but looking strictly at an on-page perspective there are a number of things that you should bear in mind.
The navigation area is on every page (normally) of your website, is it built in clear concise html or are you employing JS? If its the latter then be sure that you have spiderable versions so that spiders can find their way through your site.
Also, if you ARE using Javascript you would probably be advised to investigate the potential of using "real" html as its much lower on resources and overall size so it increases the pageload time and reduces the page size overall.
Is the nav area keyword rich if not, why not, its valid page real estate and it should be full of the keywords that you want to focus your site on. Be careful not to try and change the navigation anchor text from one page to another as there is evidence that this isnt optimal.
Are you linking to just the pages that you shoulttd be? Bear in mind that your linkjuice is being distributed amongst all the pages that you are including in it, therefore if you are linking out to 80 or 100 pages in your navigation, the total amount of strength going to each page is relatively minimal.




