The first downside is... usage of javascript! Don't do a redirect with JS. If you really really have to redirect then use .htaccess (or equivalent if you're not using apache). Make the graphic header clickable. People will expect it to be. Overboard on the ads. More is less. Google places the highest paying ads first. A well-placed ad link unit (above content usually works well) and 1 or 2 ad units, but not with lots of ads. There are a couple of pages with no content but ads: http://www.percentageproducts.com/index2.php?id=products This is a TOS violation, so should you put descriptions for each category, at least then there is some content. I clicked market place and this took me to clickbank. A big turn off. Better to have a page actually called market place, throw in a sales pitch and then offer up the link so that people can go there if they want to. Good luck.
Your product content seems to be a bit buried (you have to click on either of the two links). It could be benficial to show more content up front....sample a few of the books and then click to see the rest. Overall looks pretty good though. Definitely trim back the ads a bit - it can get annoying fast for a site visitor (myself included).
Good luck with your site, mate. I like your ad link unit placement. You'll have to let us know how it works out for you.
On your contacts page, why is your email address a picture rather than text (not even a mailto??) You could give users a simple form to fill in to contact you alongside listing your email address. There's no email validation on your freebies page where you ask people to refer your site. I just entered asdasdas as an email address and got away with it. On your freebies page, all the urls should be clickable. People hate copy and paste when they can just do it with a click
Thanks! rep added Yeah I don't know how to implement email validation. Make them all clickable? That will take hours man, should I really do it?