Jquery extract text with regular expression on complete visible text of web page

I am aware of the jQuery regex plugin of James Padolsey: http://james.padolsey.com/javascript/regex-selector-for-jquery/

But I need something different:

1. The regular expression should search in the whole visible text of the web page.
2. I want to get the text itself, not the element containing them.

The following will match requirement 1, but not 2:

$('*').filter(function() {
    return this.text().match(/\d\d\d/);
});

Any idea how i can do this with a good performance?