9
I find that having everything in one huge $(document).ready leads to messy code thats hard to read.
I often prefer to split it up and place a separate $(document).ready() for every part of the system that needs stuff added to it. This is especially nice for larger, modular, systems, where you dynamically add blocks of html, events and stuff.
For me it all boils down to what is most beneficial for you as a developer in a certain case.
But as @Codesleuth commented: very often you don't need to put stuff inside the $(document).ready(), you only need it when you need to be sure the DOM is in a consistant and known state for heavy manipulation etc.