ofca

// based on https://gist.github.com/Potfur/5576225 & https://github.com/james2doyle/saltjs
// more info: https://plus.google.com/109231487156400680487/posts/63eZzzrBSb6
window.$ = function(s) {
    var c = {
        '#': 'ById',
        '.': 'sByClassName',
        '@': 'sByName',
        '=': 'sByTagName'}[s[0]];
    return document[c?'getElement'+c:'querySelectorAll'](s.slice(1))
};

potfur

window.S = function(s) {
    return document[{
        '#': 'getElementById',
        '.': 'getElementsByClassName',
        '@': 'getElementsByName',
        '=': 'getElementsByTagName'}[s[0]]
        || 'querySelectorAll'](s.slice(1))
};

// [S('#header'), S('.container'), S('?div')]