No Algorithm: Just a list with the ability to filter and slice in many different ways, make me do the work, old school. The default list could be a feed of the most recently created markets or something.

According to My Interests: Start building up a profile of what I bet on, feed me more similar of the same.

Money: Feed me (and by extension everyone) a list of the biggest markets. Just let the biggest markets dominate and feed everyone in there.

Volatility: Feed me the (and by extension everyone) the highest volatility markets. Whatever is changing the most relative to everything else should dominate and feed everyone in there.