If you don't link to your pages, why should someone else?

And why would Google keep them in it's index, if you don't even think they're valuable enough to be linked to? Did you ever experience pages being hit by GoogleBot, staying in the index for a few days and then being dropped for no apparent reason? Now you know why - or at least one main reason why...

I'm not talking about getting links from different domains, but each page on your site should have at least one internal link pointing to it. And at least one static route from your home page to each page.

What does this mean? Simply put, there should be one chain as bellow leading to each page, and this chain should be relatively stable:

Homepage -> pageA -> pageB -> pageInQuestion

And relatively short, some would say max 2 clicks away from home page. Now we all know that's not really possible for large sites, without clogging your pages with links. But, even staying inline with Google's 100 links per page scheme:

2 clicks away - 10,000 pages

3 clicks away - 1,000,000 pages

4 clicks away - you'll never get those many pages in Google anyway:)

So you get my point - have whatever navigation structure works best for your visitors. Have a stable, pyramidal sitemap like structure for Google. And supplement it with XML sitemaps. This gives the best chances that GoogleBot will find, index and keep your pages.

Don't forget to use Google's webmaster tools to check what incomming links (internal and external) each page receives.