All about Chinese radicals:

Very useful links

These links/online dictionaries will help you better understand the important meaning and the evolution of Chinese characters! 

1. http://chinese-characters.org/radical/
2. http://www.archchinese.com/arch_chinese_radicals.html
3. http://www.mdbg.net/chindict/chindict.php?page=radicals
4. http://www.prebabel.info/bab002.htm