Bruce
I have read the post 3 times and like Frank, I needed a little time to digest the whole thing and see the whole picture. Since I do not have an active IndexU site, I don't know how valuable my opinion would be.
1: Positive - This would be a good marketing tool for IndexU. I am sure you would get people buying the script for this feature alone. I mean, who is going to pass up the free money. I would, but that is a different story. With that, may come a negative side.
2: The negative - You get people buying the script and putting up multiple link farms filled with categories and links from dmoz and making money for doing nothing. You would have to have a moderator to approve and deny sites being included in the revenue sharing. The script could still send the submissions to anyone who had the plugin activated, but only the sites included in the program would get a portion of the revenue. You would have to have some standards set for inclusion into the program.
3: You would have to have a moderator for the link submissions. I would guess there would be a large number of sites submitted on a daily basis. Frank knows what it is like to have a backlog of a couple hundred sites to approve or deny. The task would be tedious and boring.
4: The person moderating the listings would need to get paid too. Let's just say you pay the moderator 1% (pulling that number from nowhere) of each link that is approved from the submitted links. The moderator would need to be moderated because he might be broke that week and needs the money for strippers
. Maybe I am thinking too far into it, but I could see a moderator approving junky links because he gets paid for each listing he approves.
Maybe you could set up a forum for users of the program so if the moderator starts slipping his standards with the approvals, the users can voice their opinions to him/her and you or whomever can get him back on track.
5: Can this plugin even be created? In my opinion with some effort in setting standards, it would be a great program and a revenue builder for IndexU. But, can it be done? I don't even know where I would start with a plugin like that. I have a general idea of how price comparison sites work where you submit a feed file and submit it via ftp. Then the comparison site reads from that file to create it's listings. Maybe it would work in a similar fashion. Maybe you already have the plugin done and I am just wasting space with this paragraph.
Overall, I think you are onto something good, if it can be done. I would set the standards high and lower them if needed. Make sure you have a detailed plan on listing standards. Make sure it is moderated fairly. Make sure you listen to the program members about requests and issues they have with how it is run.
One last thing. Can I be the moderator? I am broke and I need money for these greedy money hungry strippers. 
Regards
Wayne
For questions related to any mods I developed, please contact me by pm or email at webmaster [at] scriptdragon [dot] com