Ways to throttle ajax requests

I'm using the following code (written by another user) to throttle ajax requests in a livesearch function:

JSFiddle if you prefer a demo: http://jsfiddle.net/4xLVp/

It seems buggy, though. Clearing values with Ctrl+shift+back-arrow, and typing again causes a flurry of requests. Blank values also cause a request. It dones't seem right, especially compared to jQuery UI autocomplete, where request delays seem more measured.

    $('##tag-search').keyup(function() {
        var elem = $(this);
        if (elem.val().length >= 2) {
            elem.data('search',search).clearQueue().stop().delay(1000).queue(function() {
                $.ajax({ // ajax stuff
                    'success': function(data){ /*show result*/ }
                });
                if (elem.data('search') !=  string) return;
            });                                             
        } else if (string.length <= 1) { /*show original content*/ }
    });

Is there a better way to handle this?