Do you look for a PC app or a smartphone app?

1. I regularly use trainchinese on my Android tablet:

http://www.trainchinese.com/v1/a_user/index.php

Have a look, I really think it's a great app!

2. Another one which also allows to search for characters by radicals is Xiaoma Hanzi which you'll find here:

http://www.androidzoom.com/android_applications/books_and_reference/xiaoma-hanzi-chinese-character_njlx.html