My suggestions are these:
- Make both sides reorderable (My Games and Top 12)
- Make it so dragging from My Games to Top 12 adds the game where you place it. Get rid of the drop box and make the entire side capable
- Make it so dragging from Top 12 to My Games removes the game from Top 12. There's not a way (that I can find) to do this other than the hassle described above
And just something else slightly related, a good source for game covers for all consoles would be The Cover Project. They have extremely high quality cover scans that could be scaled down and used on this site.
And speaking of scaling down, the covers really should all be resized instead of relying on the browser to do it. It'd save server bandwidth, and look better too. It'd also help to equalize the range of different cover sizes.