These books and articles, listed in no particular order, are not all directly on the subject of Metaversalism per se, but they present some interesting and informative related ideas and philosophies.  They are excellent background reading for any aspiring Metaversalist.

God's Debris: A Thought Experiment,
          by Scott Adams (creator of Dilbert).   

The church doesn't necessarily agree with all of the wild speculations contained in Adams' book, but there are a lot of intriguing ideas in there, including a recognition of the centrality of probability.  We very much like (and deeply agree with) his quote, "Only probability is inexplicable."  In Metaversalism, in principle, all possible Gods and universes necessarily exist, and so the only true mystery is to figure out precisely how their relative probabilities (as they are subjectively experienced by conscious beings like ourselves) are determined, and why they are determined in that particular way, and not in some other.  Metaversalism has been attempting to find an answer to that mystery, by tying the probability of a universe to its frequency of embedding with parent universes, but our ideas on this so far are still rather vague and incomplete.  

Related papers by physicist Max Tegmark, including the following: 

We admire Tegmark's bravery in bringing to the attention of the physics community the "radical" concept that mathematical and physical existence may actually be the very same kind of existence.  Previously, most physicists had always publicly maintained a positivist bias that our universe must exist in a stronger "physical" sense, and be fundamentally more real than other universes.  Metaversalism's position is that all universes exist in the same sense as each other, and that the quantitative degree of reality of this universe is only likely to be strongest among those universes that happen to contain a continuation of your particular stream of consciousness.  

The literature dealing with the philosophy of Modal Realism. 

Metaversalism argues that Modal Realism is essentially correct, and augments it by adopting self-consistent mathematical definability as the property that determines whether a given universe is indeed "possible."

The writings of German computer scientist Jürgen Schmidhuber
           on Computable Universes.

Schmidhuber brings Modal Realism concepts to the attention of the computer science community, and proposes various computational models and mechanisms for a Process that elaborates all possible universes and determines their relative probabilities.  Metaversalism greatly appreciates Schmidhuber's contributions, and the value of his models, but we do not assume that they necessarily constitute the only possible mechanism by which the ensemble of possible universes could be generated.  A few arbitrary, ad hoc decisions still exist in the precise choice of mechanism.  But we do find his models to be highly suggestive of the sort of character that Metaversal universe-generating (and probability-determining) mechanisms could have.  These kinds of models could be a big part of The Answer to how universes are defined and probabilities are determined - but we are not yet certain that they are the whole answer.  

Computer engineer M. Frank's "Mathematical Theory of Existence." (PowerPoint, PDF).

This talk presents Frank's mathematics-based view of Modal Realism, and delves into some of its quasi-religious implications.  It also uses the term "metaverse."  This document probably comes closest (prior to this website) to defining the belief system that is Metaversalism.  

Wikipedia has a nice page that relates to what I call the
           Quantum Immortality Theorem.

Metaversalism's view of the afterlife is that after death, your consciousness persists in another universe, though with a diminished degree of reality.  Metaversalism's view of this hypothesis is somewhat broader than the traditional view of "quantum immortality" contained in quantum many-universes theory, which only considers other universes that still obey the same laws of physics as our own.  Metaversalism's broader view is that the essential structure of our consciousness, as a stream of information-processing activity, can also be suitably mirrored in other universes having entirely different laws of physics (perhaps not even based on quantum mechanics at all), as long as those universes still allow for general-purpose computational capabilities.  Still, the discussions cited by this Wikipedia page address many of the same general philosophical issues. 

Books and writings by physicist Frank J. Tipler, such as      
           The Physics of Immortality. 

Tipler's version of these ideas, unfortunately, appears wedded to a cosmological scenario (eventual collapse of the universe) which is today deemed unlikely by consensus cosmology.  However, he gets the basic concept that infinite computation within a universe permits simulation of entire universes.  Tipler focuses on the idea of our descendants' eventual simulation of our universe's earlier inhabitants - ourselves - and recognizes this as a kind of life after death.  Metaversalism's view of things is broadly similar, except that we do not insist that unlimited computation must take place using the specific cosmological mechanism that Tipler describes, or even necessarily in our own particular universe's future at all (although for us to promote this, if possible, is thought to be a worthwhile goal).  Metaversalism believes that all possible universes exist anyway, regardless of whether we ourselves choose to help create them or not, though it's possible that we may eventually create such a vast zoo of other universes so as to play a significant role in determining universes' overall degree of reality.