Topic: Add two more beta only minerals
Right now, trading is functionally irrelevant to the biggest beta organizations. If you have one, you pretty much just need titan (which you can get yourself) and you're golden. Market whar?! This potential for the creation of autarkic models of corporate production is currently taking a giant dump on the game and on new players. It is double plus ungood.
Adding two more minerals and splitting each of the now three beta minerals so that they're only found on two of the six islands would nigh on require trade as you'd have no way to be completely self sufficient from an industrial standpoint.
If beta corps have to trade, we'll see more industrial activity all over the place and, more importantly, more people transiting between alpha and beta -- haulaz ***. We'll also see a rise in the importance of nic, as straight 1 for 1 trades of minerals would be irritating to pull off. A good thing!
Another thing that should be added, but isn't strictly speaking necessary, is a way to transmute titan into each of the beta minerals via an extremely inefficient process. While it might seem silly to make it possible to dodge past the beta requirement, it's critical that there be some sort of route for avoiding bottlenecks of one kind or another. EVE is currently going through a technetium bottleneck, and it has made some players fabulously rich (and spread rumors of illegal RMTing of the unlimited in game wealth fountaining out of tech moons) due to an error in usage calculations by the developers. So having an alternate path is probably a good thing, even if it costs two arms and a leg to pull it off.
tl;dr: increase the number of beta only minerals from one to three, and make each one exclusive to two beta islands. This will increase trade and make impossible a single island system of autarky as currently exists.