Amazon Flyouts 
These graphics are featured in the sub navigation where you can hover over from the Shop by Department, within the Gateway page.
Flyout graphics have the ability to let graphics "pop" out from the right or bottom of the borders. Therefore transparency is needed, by saving it out as PNG-24 file. Also for efficient loading, I would use a 3rd party app (tinypng.com) for better optimized compression.
Here are a couple of examples of multiple products that are shot individually. That I would then take to Photoshop, remove the background and scale it appropriately. Also I add shadows with the brush tool and backgrounds if applicable.
The above samples, for each column the left side are called "Blackbelt" version whereas the right side are "Classic". The main difference is that Classic version has the Amazon orange for the header. The Gateway team typically request both versions for A/B testing. Sometimes, links are rearranged and added/removed for new departments or holiday gift guide as shown from top to bottom row. The specs for these graphics are constantly always changing, so it is vital to be on top of it.