I would like to suggest

1. Add stackapps.com to list of sites
2. Allow the common "upside-down" unicode characters that have become trendy lately (and some users are using in their names now).

Diff format, tested and working for me in Chrome:

    --- 68252.user.js.orig	2011-08-13 11:15:22.000000000 -0700
    +++ 68252.user.js	2011-08-13 11:15:43.000000000 -0700
    @@ -15,6 +15,7 @@
     // @include        http://meta.answers.onstartups.com/*
     // @include        http://mathoverflow.net/*
     // @include        http://area51.stackexchange.com/proposals/*
    +// @include        http://stackapps.com/*
     // @author         Benjamin Dumke
     // ==/UserScript==
     
    @@ -82,7 +83,10 @@
                                 ,'\u00e0','\u00e1','\u00e2','\u00e3','\u00e4','\u00e5','\u00e6','\u00e7'
                                 ,'\u00e8','\u00e9','\u00ea','\u00eb','\u00ec','\u00ed','\u00ee','\u00ef'
                                 ,'\u00f1','\u00f2','\u00f3','\u00f4','\u00f5','\u00f6'         
    -                            ,'\u00f8','\u00f9','\u00fa','\u00fb','\u00fc','\u00fd'         ,'\u00ff').join('');
    +                            ,'\u00f8','\u00f9','\u00fa','\u00fb','\u00fc','\u00fd'         ,'\u00ff'
    +                            // upside-down lowercase from http://www.fileformat.info/convert/text/upside-down-map.htm
    +                            ,'\u0250','\u0254','\u01dd','\u025f','\u0183','\u0265','\u0131','\u027e'
    +                            ,'\u029e','\u0283','\u026f','\u0279','\u0287','\u028c','\u028d','\u028e').join('');
     
         var bad = new RegExp("[^" + goodletters + "\\w.'-]", "ig");