I recently launched 3 websites (within the past 7-10 months) that had been steadily increasing in the rankings on Google search up until this past weekend, when I noticed a huge drop across most of my tracked keywords. The websites are e-commerce sites. This drop coincided with the exact date and time (September 28) of Google's most recent Panda update, Panda 2.5. I am wondering what the implications might be for new websites like mine with Panda 2.5. What is this most recent algorithm change targeting? Duplicate content, poor content, bad URLs? Any new information on this would be of help.
In a quick glance at your sites I noticed some things that might be impacting your ranking.
I didn't do a full link analysis but it looks like most of your links come from your other sites with very few links from outside this circle. These links were probably discounted in value since it probably triggered an anti-link-wheel algorithm. You need to work on obtaining outside links, especially ones from stronger, well-established, sites that Google trusts. External links and their strength is what will make or break your site in SEO terms. I wouldn't remove the links you already have since losing a significant number of links, even if they're discounted, can cause even more damage.
Beyond that, there are a few on-site tweaks that you could make, such as using more keyword friendly page names (rather than SKUs), but I wouldn't make that change now since it looks like most of your pages are indexed. Increasing the amount of content on these pages might help some but it will be a slow process.