I think a royalty feature would be fantastic. For those of us that sell items that we owe commission to others on, on multiple products, it would be great to keep track of. Even if they had to be an affiliate, link them up somehow.
I sell an ebook for $10. The author (not me) gets 50% of sales. But, on another one he only gets 30%. I would have to always tally up everything for every item... get tedious.