subcategory solution

[eluser]cahva[/eluser]
I've done ecommerce site myself with SEO friendly urls. I suggest you create 2 controllers: product and category. Use _remap() method in both of them(so everything after product or category points to that method). After that you can inspect what has passed to the controller and fetch product/category according to that.

Couple of pointers:
Save the full seo path(call it seo, slug whatever) to databse. For example for the product1, save "shoes/blue-shoes/summer-shoes/product1" as the seo url. With this saved, you can do search from the database easily. I did the mistake NOT to save the path in the first place and had to "travel" the segments one by one, which ofcourse caused overhead.

In my shop I have only one controller named shop. But being wiser now, it would have been better to have category and product controller as you can do seo search more easily according to which controller you are at(search for product seo if you are on product controller and search for category seo if you are on category controller).