DOM text search/replace plugin for jQuery.

gistfile1.js

(function($){
    $.fn.textReplace = function(map, patterns) {
        map = map || {};
        patterns = patterns || [];

        $('*', this).contents().filter(function() {
            return ((this.nodeType == 3));
        }).each(function() {
            var old_text = $.trim(this.nodeValue);
            var new_text;

            if (map.hasOwnProperty(old_text)) {
                new_text = map[old_text];
                if (typeof new_text == "function") {
                    new_text = new_text(this);
                }
            } else {
                for (var i in patterns) {
                    var pattern = patterns[i][0];
                    var replacement = patterns[i][1];

                    if (old_text.match(pattern)) {
                        if (typeof replacement == "function") {
                            new_text = replacement(this);
                        } else {
                            new_text = old_text.replace(pattern, replacement);
                        }
                        break;
                    }
                }
            }

            if (new_text != undefined) {
                this.nodeValue = new_text;
            }

        });
    }
})(jQuery);

See it in action: http://jsfiddle.net/8w55h/