Try like this:

$.ajax({
    type: 'POST',
    // make sure you respect the same origin policy with this url:
    // http://en.wikipedia.org/wiki/Same_origin_policy
    url: 'http://nakolesah.ru/',
    data: { 
        'foo': 'bar', 
        'ca$libri': 'no$libri' // <-- the $ sign in the parameter name seems unusual, I would avoid it
    },
    success: function(msg){
        alert('wow' + msg);
    }
});

$.ajax({
    type: 'POST',    
    url:'http://nakolesah.ru/',
    data:'foo='+ bar+'&calibri='+ nolibri,
    success: function(msg){
        alert('wow' + msg);
    }
});

I see that they did not understand your question.

Answer is: add "traditional" parameter to your ajax call like this:

$.ajax({
  traditional: true,
  type: "POST",
  url: url,
  data: custom,
  success: ok,
  dataType: "json"
});

And it will work with parameters PASSED AS A STRING.