Parametrized $\diamondsuit$ principles
  We will present a collection of guessing principles which have a similar relationship to $\diamond$ as cardinal invariants of the continuum have to $\CH$. The purpose is to provide a means for systematically analyzing $\diamond$ and its consequences. It also provides for a unified approach for understanding the status of a number of consequences of $\CH$ and $\diamond$ in models such as those of Laver, Miller, and Sacks. 
Justin Tatch Moore, Michael Hru\v{s}\'ak, Mirna D\v{z}amonja