I get a regular update from a site called Press Release Ireland, most particularly with regards to whatever they decide to be “consumer” related issues.
ShopUSA.ie links to the web sites of many popular American stores so you can window shop before you leave your sitting room! These sites may not show everything that is in store but it will give you a good idea on what to look for when you arrive in the USA.
I’ve had a look through the site myself and while it does have a fair bit of information, and lots of links, it just comes across as a bit flat. A major thing that I think is missing is a map of New York City – since it seems to be focused on that region.