Read preferences for replica sets

[spl]

I'm putting this out there because I don't see how to do it right now, but I could easily be missing something.

Currently, we can create a replica set, but, unfortunately, we only get Pipes for the primary and secondary, which means we have to choose one or the other for a connection.

Preferably, we should be able to set a read preference to tell the replica set that we prefer read data from the primary or secondary members of the replica set.