The Art Portal is already a very good platform for artists but I feel that an additional feature of being able to post image albums/sets/groups or whatever you'd call them would be a great improvement..
For instance being able to submit multiple images as an album would be fantastic for pictures that have alt versions so you don't flood the portal with multiples of what are essentially the same image since as of now the best you can do is link to an outside gallery that holds them. And if such a system would be implemented I would think a simple addition to the previews seen on the portal would suffice for showing that said picture is actually an album.
Now my mock up here was done in a minute but it shows the idea I'm putting down.
There are ways to make it all posh and proper if you really wanted to like making it fade between the various previews of the images in the album but asides from how it looks an addition like this would be quite a nice upgrade for the portal, or at least I think so.
Last point would be a limit on how many images could be in an album, a bare minimum I would personally say would be at least 4 with a hard maximum being at 10, any more than that is just ridiculous but that's my take, I would ask what your guy's take on this is and what you would personally have for a limit of images to an album/set/grouping or whatever you'd call it.