I'm always agreeable on new things. This sort of issue has come up before. Some folks asked if it would be ok to do link trades on their free sites. I said "sure", some said "no way". It didn't really work out that well. I seemed as if everyone was linking out from their free sites and not really linking back to them. In other words, they were leaching the PR they were getting from their linklist listings to promote other sites.
The other side of that coin is that most search engines don't like stagnant sites. I'd love to see the freesites that I'm listing get changed occasionally, new inbound links, etc. The problem there is I can see all the cheaters out there rubbing their hands together and snickering, just dreaming of all the ways they can abuse something like that.
I have to give it some thought. Maybe just let your trusted submmitters do that (yes, I have one of those lists too
) and tell everyone else to pound sand.