Mandarin Learning Website

Radical / Guratan
http://www.archchinese.com/arch_chinese_radicals.html
http://www.hackingchinese.com/kickstart-your-character-learning-with-the-100-most-common-radicals/
http://www.zhongwen.com/
http://www.chtsai.net/radicals/
(need flash player)

Conversation
http://www.chineselearner.com/speaking/
(need flash player)
http://www.hellomandarin.com/ilovechinese/conversation/
(need windows media player & internet explorer)
http://www.chinese-tools.com/learn/chinese/contents.html
(caligraphy step by step & need media player)
http://carlgene.com/blog/2010/06/100-english-and-chinese-conversation-topics/
(text & question only)
http://www.china.org.cn/e-learning/1.htm
(need real player)

of course some website need good speaker, if you want listen conversation with your multimedia player.

Grammar
http://resources.allsetlearning.com/chinese/grammar/