HTTPS support, changes your own rep in the top bar as well.

Great script :P

    // ==UserScript==
    // @name           hex stack overflow rep
    // @namespace      stackoverflow
    // @description    Displays user's rep in hexadecimal on stack overflow
    // @include       http*://*stackoverflow.com/*
    // @include       http*://*superuser.com/*
    // @include       http*://*serverfault.com/*
    // @include       http*://*askubuntu.com/*
    // @include       http*://*.stackexchange.com/*
    // @include       http*://*stackapps.com/*
    // @author         a stone arachnid
    // ==/UserScript==
    
    !function() {
       function with_jquery(f) {
        var script = document.createElement("script");
        script.type = "text/javascript";
        script.textContent = "(" + f.toString() + ")(jQuery)";
        document.body.appendChild(script);
      }; 
    
      with_jquery(function() {
        function calculate(x){
          var title = $(x).attr('title'),
          text = $(x).text(),
          rep = 1;
    
          if(text.indexOf('k') < 0){rep = parseInt(text.replace(/,/g, ''));}
          else{
            rep = parseInt(title.replace(/\D/g, ''));
    
            //if no rep was in the tooltip, convert the truncated rep to hex
            if(isNaN(rep)) rep = Math.round(1000 * parseFloat(text.replace(/[k,]/gi, '')));
          }
    
          $(x).text('0x' + rep.toString(16).toUpperCase()).attr('title',rep);
        }
        $('.-rep').each(function() {
          calculate(this);
        });
        $('.reputation-score').each(function() {
          calculate(this);
        });
      });
    
    }();