With the recent surge of users from the fast track network that aren't used to sharing their files, I would like to see a feature that would always give a higher priority to people that are sharing and want to download from you. That way, if you are sharing files, then you could get your downloads faster, and if you decide not to share, then you have to wait your turn in line.
Limewire has a feature kind of like this, and I think that it would encourage people to share files. I'm just sick of seeing the graphs at limewire that show 370,000 clients on gNet, but only ~55,000 clients accepting incoming connections.

GuyOnTheCouch