SEO tips = better search engine ranking

Travel site's crazy PageRank?

I have according to Yahoo, 738 links coming into my travel Amazon bookstore. The home page is PR3. However, my travel sites page is PR 4. That's so weird because I have so few links from other sites pointing at the internal pages and so many pointing at the homepage. Other pages on the main menu are also PR 4 like my Europe travel books page. OK, I can understand that.

But why are pages that get a link from the homepage and the travel sites page (but not the other pages) also show PR 4 like this Hawaii site page? And with the same links, my advertising page shows PR 0. Also showing PR 0 is this travel DVD page with a link from the homepage (and that's the only link). Oh and now the hompeage is PR 4. What's going on here? I swear it was PR 3 a moment ago.

Now I see. The coder who did this site for me was not an SEO... It seems that my domain/ is PR 3 while my domain/index.php is PR 4. Rookie mistake that I should have seen a long time ago. I still don't see why 501 internal links = PR 4 when 783 externals = PR 3 but I just have to live with that ambiguity...