This website has a lot of great tools for learning Mandarin Chinese. One of the main highlights is a selection of handy software tools for learning and using Chinese including a web-based flash card software tool. Some of the other highlights are links to and tools for translation, learning to draw Chinese characters, Chinese encoding detector, currency converter, Chinese dictionaries and a Pinyin converter.
It's the kind of site that you have to check out to fully comprehend - there is a lot there.
"These pages hope to provide tools to assist people in learning and using the beautiful Chinese language. From the novice Chinese language student to the advanced programmer, I hope there is something here for everyone. Rather than being a Chinese language course, it provides tools to people who are already studying and using Chinese."
Mandarin Chinese Language