array-unique

// This method is kind of cheeky in its implementation. 
// It uses the JavaScript’s object to add every item in the array as key.
// As we all know, objects accepts only unique keys and sure we did capitalize on that.

Array.prototype.unique = function() {
    var o = {}, i, l = this.length, r = [];
    for(i=0; i<l;i+=1) o[this[i]] = this[i];
    for(i in o) r.push(o[i]);
    return r;
};