Here is an idea, how about
1. An index of top referrers. This could be displayed in the wallet itself.
2. An ability to automatically subscribe voting power to the top referrers.
The idea being that voting power could be correlated with how successful a participant is at bringing new money into the ecosystem. Referrers bring new money into the ecosystem and it can be measured, so their good reputation could be rewarded with voting power.
Anyone who brings in new money increases the Bitshares market cap which benefits the whole ecosystem. So the top referrers are objectively providing benefit. If I could automatically through some checkbox reward the top referrers then it would give power to the people most successful at growing Bitshares.