When designing your URL scheme you might consider trying to make hackable URLs. By this I mean to say that your URLs should be able to support user manipulation. A URL such as
Product/Details/2 is fine for displaying a product, but it doesn't show any information for Google to slurp up when ranking your site; it also doesn't provide any additional navigational abilities to your viewing customer, it just shows a product. Now take the following URL:
Catalog/Computers/Laptops/Toshiba/Satellite-650. With this sort of URL, you are providing your customers with the ability to remove the specific laptop
Satellite-650 and display all of the laptops that Toshiba makes. You could further remove the
Toshiba from ...