Kind of Important wrote...
Personally, I'm a big fan of the multiverse theory. I really love quantum mechanics and things of that nature (being the nerd I am) and this is pretty much the top of the pile of cool shit that is plausible.
Not so much of multiple universes from the big bang, but of the idea, that each chocie in this world creates a seperate universe that varies slightly depending on the choice. (So, say in this universe you chose to buy a certain type of car. At that exact time, another universe split off from that, and in the other universe, you bought a different one. Something like that.) And in which case there would already be untold number of universes, probably far beyond any ability to count them.
Let me take you post to illustrate a thought: If every possibility creates or equals another universe, that would be fucking lots of universes. lets take 1g of hydrogen and measure the spin of just the electrons. they can be "up" or "down" (you see this is a very easy and small example). that makes about 10^23 (10 to the power of 23) electrons und thus 2^(10^23) possible configurations. thats more than 10^(10^22), a one with 10^22 zeros behind it. for example: the universe has just about 10^80 atoms, thats just a 10 with 80 zeros... I would say a multiverse of that kind is not very economical.
It just seems very unlikely to me. I really appreciate it in comic books, movies, etc. though.