I've seen a lot of Iron Man hoodies over the years, but this is hands down the best. It's actually built with the armor parts.
This hoodie was created by Etsy user iamknight, and it combines the abdomen and elbows of the Mark VIII armor with the chest and shoulders of the Mark VII armor and has a detachable hood.
You will have to fork over a good amount of cash for this awesomeness though, as it costs $450. If you want to get yourself one head on over to the creator's Etsy page.