Can you have multiple $(document).ready(function(){ ... }); sections?

You can have multiple ones, but it's not always the neatest thing to do. Try not to overuse them, as it will seriously affect readability. Other than that , it's perfectly legal. See the below:

http://www.learningjquery.com/2006/09/multiple-document-ready

Try this out:

$(document).ready(function() {
    alert('Hello Tom!');
});

$(document).ready(function() {
    alert('Hello Jeff!');
});

$(document).ready(function() {
    alert('Hello Dexter!');
});

You'll find that it's equivalent to this, note the order of execution:

$(document).ready(function() {
    alert('Hello Tom!');
    alert('Hello Jeff!');
    alert('Hello Dexter!');
});

It's also worth noting that a function defined within one $(document).ready block cannot be called from another $(document).ready block, I just ran this test:

$(document).ready(function() {
    alert('hello1');
    function saySomething() {
        alert('something');
    }
    saySomething();

});
$(document).ready(function() {
    alert('hello2');
    saySomething();
}); 

output was:

hello1
something
hello2

You can use multiple. But you can also use multiple functions inside one document.ready as well:

$(document).ready(function() {
    // Jquery
    $('.hide').hide();
    $('.test').each(function() {
       $(this).fadeIn();
    });

    // Reqular JS
    function test(word) {
       alert(word);
    }
    test('hello!');
});

Yes you can easily have multiple blocks. Just be careful with dependencies between them as the evaluation order might not be what you expect.