This is a very basic user script which does the following:

* Checks the review homepage if there's anything you can review

  * If so, it changes the title to `(`_`n`_`) old_title` where _`n`_ is the number of review tasks you can perform
  * If not, it refreshes the page in 15 seconds

[Install the script][1]

This is the script:

    // ==UserScript==
    // @name        Review Stalker
    // @namespace   http://camilstaps.nl
    // @description Stalks the StackExchange review pages
    // @include     http://*stackexchange.com/review
    // @include     http://*stackexchange.com/review/
    // @include     http://stackoverflow.com/review
    // @include     http://stackoverflow.com/review/
    // @include     http://serverfault.com/review
    // @include     http://serverfault.com/review/
    // @include     http://superuser.com/review
    // @include     http://superuser.com/review/
    // @include     http://askubuntu.com/review
    // @include     http://askubuntu.com/review/
    // @require     http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js
    // @version     1
    // @grant       
    // ==/UserScript==

    var reviews_avail = 0;
    var title = document.title;

    $('.dashboard-num').each(function(index){
        if (!$(this).parent().hasClass('dashboard-faded')) {
            reviews_avail += parseInt($(this).attr('title'));
        }
    });
    if (reviews_avail) {
        window.setTimeout(function(){
            if (title == document.title) {
                document.title = "(" + reviews_avail + ") " + title;
            } else {
                document.title = title;
            }
        }, 300);
    } else {
        window.setTimeout(function(){
            window.location = window.location;
        }, 15000);
    }

[Install the script][1]

[1]: http://userscripts.org/scripts/source/167095.user.js