Since many are likely using Listium to create wishlists. I think one amazing feature that could be implemented would be the ability to the grab product images from a given URL. Wishlist creators like ThingsToGetMe(dot)com do this, and so being able to do this instead of having to copy an image, grab the url for the image, or even saving it and uploading it.
If this feature is implemented, perhaps it could be programmed so the images are grabbed automatically when adding an item to the list with a given URL, or that this is something that is done in the background automatically for items already in a list (which is what some bookmarking services like Raindrop(dot)io does).